View source for International Mathematical Olympiad

{{Short description|Annual high school maths competition}}
{{Use dmy dates|date=July 2022}}

[[File:IMO logo.svg|thumb|Logo of the International Mathematical Olympiad]]

The '''International Mathematical Olympiad''', abbreviated as '''IMO''', is a [[mathematical olympiad]] for [[Student competition|pre-university students]], and is the oldest of the [[International Science Olympiad]]s.<ref>{{cite web|url=https://olympiads.win.tue.nl/imo/|title=International Mathematics Olympiad (IMO)|date=2008-02-01}}</ref> It is widely regarded as the most prestigious mathematical competition in the world. The first IMO was held in [[Socialist Republic of Romania|Romania]] in 1959. It has since been held annually, except in 1980. More than 100 countries participate. Each country sends a team of up to six students,<ref name = "more"/> plus one team leader, one deputy leader, and observers.<ref>{{cite web|url=http://www.akamai.com/html/about/press/releases/2001/press_070401.html|title=The International Mathematical Olympiad 2001 Presented by the Akamai Foundation Opens Today in Washington, D.C.|access-date=2008-03-05}}</ref>

Awards are given to approximately the top-scoring 50% of the individual contestants. Teams are not officially recognized—all scores are given only to individual contestants, but team scoring is unofficially compared more than individual scores.<ref>{{cite web|url=https://www.imo-register.org.uk/1992-report.html|title=33rd International Mathematical Olympiad|access-date=2008-03-05|date=1992-07-21|author=Tony Gardiner|publisher=University of Birmingham}}</ref>

==Question type==
The content ranges from extremely difficult [[algebra]] and pre-calculus problems to problems in branches of mathematics not conventionally covered in secondary or high school and often not at university level either, such as [[Projective geometry|projective]] and [[complex geometry]], [[functional equations]], [[combinatorics]], and well-grounded [[number theory]], of which extensive knowledge of theorems is required. Calculus, though allowed in solutions, is never required, as there is a principle that anyone with a basic understanding of mathematics should understand the problems, even if the solutions require a great deal more knowledge. Supporters of this principle claim that it allows more universality and creates an incentive to find elegant, deceptively simple-looking problems that nevertheless require a certain level of ingenuity, oftentimes a great deal of ingenuity, to net all points for a given IMO problem.<ref>{{cite book
 | title = Mathematical Olympiad Treasures
 | first1 = Titu | last1 = Andreescu
 | first2 = Bogdan | last2 = Enescu
 | year = 2012
 | edition = 2nd
 | page = v.
 | url = https://books.google.com/books?id=550P8T4-1BAC&pg=PR5
 | publisher = Springer
}}</ref>

==Selection process==
{{Main|International Mathematical Olympiad selection process}}
The selection process differs by country, but it often consists of a series of tests that admit fewer students at each test. Contestants must be under the age of 20 and must not be registered at any [[tertiary institution]]. Subject to these conditions, an individual may participate any number of times in the IMO.<ref name="otago">{{cite web|url=http://www.maths.otago.ac.nz/home/schools/gifted_children/olympiad.pdf|title=The International Mathematical Olympiad|access-date=2008-03-05|publisher=AMC|archive-url=https://web.archive.org/web/20080216122623/http://www.maths.otago.ac.nz/home/schools/gifted_children/olympiad.pdf|archive-date=2008-02-16|url-status=dead}}</ref>

==History==
{{see also|List of International Mathematical Olympiads}}
The first IMO was held in Romania in 1959. Since then it has been held every year (except in 1980, when it was cancelled due to internal strife in Mongolia).<ref>{{cite journal |last=Turner |first=Nura D. |title=A Historical Sketch of Olympiads: U.S.A. and International |journal=The College Mathematics Journal |volume=16 |issue=5 |year=1985 |pages=330–335 |doi=10.1080/07468342.1985.11972906 }}</ref> It was initially founded for eastern European member countries of the [[Warsaw Pact]], under the [[USSR]] bloc of influence, but later other countries participated as well.<ref name = "more"/> Because of this eastern origin, the IMOs were first hosted only in eastern European countries, and gradually spread to other nations.<ref>{{cite web|url=http://sms.math.nus.edu.sg/Simo/Simo.aspx|title=Singapore International Mathematical Olympiad (SIMO) Home Page|access-date=2008-02-04|publisher=Singapore Mathematical Society|archive-date=27 March 2003|archive-url=https://web.archive.org/web/20030327035236/http://sms.math.nus.edu.sg/Simo/Simo.aspx|url-status=dead}}</ref>

Sources differ about the cities hosting some of the early IMOs. This may be partly because leaders and students are generally housed at different locations, and partly because after the competition the students were sometimes based in multiple cities for the rest of the IMO. The exact dates cited may also differ, because of leaders arriving before the students, and at more recent IMOs the IMO Advisory Board arriving before the leaders.<ref>{{cite web|url=http://blog.medallia.com/2006/07/norwegian_students_in_internat.html|title=Norwegian Students in International Mathematical Olympiad|access-date=2008-03-05|url-status=dead|archive-url=https://web.archive.org/web/20061020100605/http://blog.medallia.com/2006/07/norwegian_students_in_internat.html|archive-date=2006-10-20}}</ref>

Several students, such as [[Lisa Sauermann]], [[Peter Scholze]], [[Reid W. Barton]], [[Nicușor Dan]] (notably elected President of Romania in 2025) and [[Ciprian Manolescu]] have [[List of International Mathematical Olympiad participants#High-scoring participants|performed exceptionally well]] in the IMO, winning multiple gold medals. Others, such as [[Terence Tao]], [[Artur Avila]], [[Grigori Perelman]], [[Ngô Bảo Châu]], [[Peter Scholze]] and [[Maryam Mirzakhani]] have gone on to become notable [[mathematician]]s. Several former participants [[List of International Mathematical Olympiad participants#Notable participants|have won awards]] such as the [[Fields Medal]].<ref>{{Harv|Lord|2001}}</ref>

Shortly after the 2016 International Mathematical Olympiad in [[Hong Kong]], [[North Korea]]n child prodigy [[Ri Jong-yol]] made his way to the [[Consulate General of South Korea, Hong Kong|South Korean consulate general]], where he sought refuge for two months. Chinese authorities eventually allowed him to leave Hong Kong on a flight to [[Seoul]]. He legally changed his name to Lee Jung-ho (이정호) after receiving South Korean citizenship. This is the only case of its kind in the IMO's history.

==Scoring and format==
The competition consists of 6 [[Mathematical problem|problems]]. The competition is held over two consecutive days with 3 problems each; each day, the contestants have four-and-a-half hours to solve three problems. Each problem is worth 7 points for a maximum total score of 42 points. [[Calculators]] are banned. [[Protractor]]s were banned relatively recently.<ref>{{cite magazine|url=https://www.edb.gov.hk/attachment/tc/curriculum-development/kla/ma/IMO/Nov20155-4online.pdf|title=IMO 2015 Report Leader's Perspective (I)|author= Law, Ka-Ho|magazine= IMOment: IMO 2016 Newsletter|issue= 5|year= 2015|page= 4}}</ref> Unlike other science olympiads, the IMO has no official syllabus and does not cover any university-level topics. The problems chosen are from various areas of secondary school mathematics, broadly classifiable as [[geometry]], [[number theory]], [[algebra]], and [[combinatorics]]. They require no knowledge of [[higher mathematics]] such as [[calculus]] and [[mathematical analysis|analysis]], and solutions are often elementary. However, they are usually disguised so as to make the solutions difficult. The problems given in the IMO are largely designed to require creativity and the ability to solve problems quickly. Thus, the prominently featured problems are algebraic [[inequality (mathematics)|inequalities]], [[complex numbers]], and [[compass and straightedge constructions|construction]]-oriented geometrical problems, though in recent years, the latter has not been as popular as before because of the algorithmic use of theorems like [[Muirhead's inequality]], and complex/analytic bashing to solve problems.{{sfnp|Olson|2004}}

Each participating country, other than the host country, may submit suggested problems to a problem selection committee provided by the host country, which reduces the submitted problems to a shortlist. The team leaders arrive at the IMO a few days in advance of the contestants and form the IMO jury, which is responsible for all the formal decisions relating to the contest, starting with selecting the six problems from the shortlist. The jury aims to order the problems so that the order in increasing difficulty is Q1, Q4, Q2, Q5, Q3, and Q6, where the first day problems Q1, Q2, and Q3 are in increasing difficulty, and the second day problems Q4, Q5, and Q6 are in increasing difficulty. The team leaders of all countries are given the problems in advance of the contestants, and thus, are kept strictly separated and observed.{{sfnp|Djukić|2006}}

Each country's marks are agreed between that country's leader and deputy leader, and coordinators provided by the host country (the leader of the team whose country submitted the problem in the case of the marks of the host country), subject to the decisions of the chief coordinator and, ultimately, a jury if any disputes cannot be resolved.<ref>{{cite web|url=http://imo.wolfram.com/facts.html|title=IMO Facts from Wolfram|access-date=2008-03-05|archive-date=29 February 2012|archive-url=https://web.archive.org/web/20120229122231/http://imo.wolfram.com/facts.html|url-status=dead}}</ref>

==Selection process==
{{main|International Mathematical Olympiad selection process}}
[[File:Geo prob diagram.svg|thumb|200px|A stage in the process of solving a problem from the [[American Invitational Mathematics Examination|AIME]], part of the United States' selection process]]
The selection process for the IMO varies greatly by country. In some countries, especially those in [[East Asia]], the selection process involves several tests of a difficulty comparable to the IMO itself.<ref>{{Harv|Liu|1998}}</ref> The Chinese contestants go through a camp.<ref>Chen, Wang. Personal interview. February 19, 2008.</ref> In others, such as the United States, possible participants go through a series of easier standalone competitions that gradually increase in difficulty. In the United States, the tests include the [[American Mathematics Competitions]], the [[American Invitational Mathematics Examination]], and the [[United States of America Junior Mathematical Olympiad]]/[[United States of America Mathematical Olympiad]], each of which is a competition in its own right. For high scorers in the final competition for the team selection, there also is a [[Mathematical Olympiad Summer Program|summer camp]], like that of China.<ref>{{cite web|url=http://www.unl.edu/amc/|title=The American Mathematics Competitions|access-date=2008-03-05|url-status=dead|archive-url=https://web.archive.org/web/20080302084024/http://www.unl.edu/amc/|archive-date=2008-03-02}}</ref>

In countries of the former [[Soviet Union]] and other eastern European countries, a team has in the past been chosen several years beforehand, and they are given special training specifically for the event. However, such methods have been discontinued in some countries.<ref>{{cite web|url=http://www.austms.org.au/Gazette/1997/Nov97/hunt.html|title=IMO 1997|access-date=2008-03-05|author=David C. Hunt|publisher=Australian Mathematical Society|archive-date=16 September 2009|archive-url=https://web.archive.org/web/20090916040353/http://www.austms.org.au/Gazette/1997/Nov97/hunt.html|url-status=dead}}</ref>

==Awards==
The participants are ranked based on their individual scores. Medals are awarded to the highest ranked participants; slightly fewer than half of them receive a medal. The cutoffs (minimum scores required to receive a gold, silver, or bronze medal respectively) are then chosen so that the numbers of gold, silver and bronze medals awarded are approximately in the ratios 1:2:3. Participants who do not win a medal but who score 7 points on at least one problem receive an honorable mention.<ref>{{cite web|url=http://imo.wolfram.com/scores/howmedals.html|title=How Medals Are Determined|access-date=2008-03-05|archive-date=1 January 2018|archive-url=https://web.archive.org/web/20180101152211/http://imo.wolfram.com/scores/howmedals.html|url-status=dead}}</ref>

Special prizes may be awarded for solutions of outstanding elegance or involving good generalisations of a problem. This last happened in 1995 ([[Nikolay Nikolov (mathematician)|Nikolay Nikolov, Bulgaria]]) and 2005 (Iurie Boreico), but was more frequent up to the early 1980s.<ref>{{cite web|url=https://olympiads.win.tue.nl/imo/imo95/imo95reg.html|title=IMO '95 regulations|access-date=2008-03-05}}</ref> The special prize in 2005 was awarded to Iurie Boreico, a student from Moldova, for his solution to Problem 3, a three-variable inequality.<ref>{{cite web|title=USA and International Mathematical Olympiads: 2006-2007 |url=https://web.williams.edu/Mathematics/sjmiller/public_html/greenchicken/otherexams/olympiad0607solns.pdf|editor-first1=Zuming|editor-last1=Feng|editor-first2=Yufei|editor-last2=Zhao}}</ref>

The rule that at most half the contestants win a medal is sometimes broken if it would cause the total number of medals to deviate too much from half the number of contestants. This last happened in 2010 (when the choice was to give either 226 (43.71%) or 266 (51.45%) of the 517 contestants (excluding the 6 from North Korea — see below) a medal),<ref name="award">{{cite web|url=http://official.imo2011.nl/year_individual_r.aspx?year=2010|title=51st International Mathematical Olympiad Results|access-date=2011-07-25|archive-url=https://web.archive.org/web/20110629113735/http://official.imo2011.nl/year_individual_r.aspx?year=2010|archive-date=2011-06-29|url-status=dead}}</ref> 2012 (when the choice was to give either 226 (41.24%) or 277 (50.55%) of the 548 contestants a medal), and 2013, when the choice was to give either 249 (47.16%) or 278 (52.65%) of the 528 contestants a medal. In these cases, slightly more than half the contestants were awarded a medal.<ref name=imo2011>{{cite web |url=https://www.imo-official.org/year_individual_r.aspx?year=2011&column=total&order=desc |title=52nd IMO 2011 – Individual results|publisher=International Mathematical Olympiad |accessdate=2022-07-17}}</ref><ref name=imo2012>{{cite web |url=https://www.imo-official.org/year_individual_r.aspx?year=2012&column=total&order=desc |title=53rd IMO 2012 – Individual results|publisher=International Mathematical Olympiad |accessdate=2022-07-17}}</ref>

[[File:IMO_2015_closing_ceremony.jpg|thumb|200px|Some of gold medal contestants during the IMO 2015 closing ceremony, Chiang Mai Thailand]]

==Penalties and bans==
North Korea was disqualified twice for cheating, once at the 32nd IMO in 1991<ref>{{cite journal
 | author-last = Woodrow |author-first = Robert E.  | title = The Olympiad corner No.129 | year = 1991 | journal = [[Crux Mathematicorum]] | volume = 17 | issue = 9 | pages = 257 | url = https://smc.math.ca/wp-content/uploads/crux-pdfs/Crux_v17n09_Nov.pdf | access-date = 2023-09-24 }}</ref> and again at the 51st IMO in 2010.<ref>{{cite web|url=https://www.imo-official.org/country_team_r.aspx?code=PRK|title=International Mathematical Olympiad: Democratic People's Republic of Korea|access-date=2010-07-17}}</ref> However, the incident in 2010 was controversial.<ref>{{cite web|url=https://www.imo-register.org.uk/2010-report.html|title=International Mathematical Olympiad 2010 UK leader's report, Almaty and Astana, Kazakhstan|author=Geoff Smith |website = UK IMO Register |access-date=2023-09-06}}</ref><ref>{{cite web|url=https://artofproblemsolving.com/community/c6h357005|title=North Korea's disqualification at IMO 2010. |website=Art of Problem Solving|access-date=2023-09-06}}</ref> There have been other cases of cheating where contestants received penalties, although these cases were not officially disclosed. (For instance, at the 34th IMO in 1993, a contestant was disqualified for bringing a pocket book of formulas, and two contestants were awarded zero points on second day's paper for bringing calculators.<ref>{{cite web|url=https://www.imo-register.org.uk/1993-report.html|title=34th International Mathematical Olympiad, Istanbul, Turkey, UK leader's report |author = Adam McBride |website = UK IMO Register |access-date=2023-11-24}}</ref>)

Russia has been banned from participating in the Olympiad since 2022 as a response to its [[Russian invasion of Ukraine|invasion of Ukraine]].<ref name=":1">{{Cite web |date=2022-03-31 |title=International Mathematical Olympiad |url=https://www.imo-official.org/ |access-date=2023-12-16 |archive-url=https://web.archive.org/web/20220331101006/https://www.imo-official.org/ |archive-date=31 March 2022 }}</ref> Nonetheless, a limited number of students (specifically, 6) are allowed to take part in the competition and receive awards, but only remotely and with their results being excluded from the unofficial team ranking. Slightly more than a half of the IMO 2021 Jury members (59 out of 107) voted in support of the sanction proposed by the IMO Board in an online voting in March 2022.<ref name=":1" />

In May 2025, a letter signed by over 700 mathematicians, amongst whom are [[Fields medal]]ists and a former Israeli IMO contestant, has called on the IMO Board to suspend the membership of Israel in the 2025 IMO for [[Gaza genocide|its war crimes in Gaza]] in the same way as the Board did to Russia. The letter cites as one of the reasons that the Palestinian IMO team members were blocked by the Israeli authorities from leaving the country for the 2024 IMO. The president of the IMO Board has refused to act, claiming that the Jury may decide during the 2025 IMO. The letter, however, accuses him of preventing the Jury from discussing the issue during the 2024 IMO by invoking a newly-added obscure regulation.<ref>{{cite news|url= https://www.theguardian.com/world/2025/jun/07/the-longest-division-can-palestinian-and-israeli-students-compete-at-the-international-maths-olympiad|title= The longest division: can Palestinian and Israeli students compete at the International Maths Olympiad?| work= The Guardian|author= Joe Hinchliffe|date=6 June 2025|access-date=28 June 2025}}</ref><ref>{{cite web|title=Mathematics and Moral Responsibility: The IMO and the Genocide in Gaza| url=https://aurdip.org/en/mathematics-and-moral-responsibility-the-imo-and-the-genocide-in-gaza/|website= AURDIP| date = 18 May 2025 | access-date= 28 June 2025}}</ref>

==Summary==

{{see also|List of International Mathematical Olympiads|List of countries by medal count at International Math Olympiad}}
[[File:IMO 2007.jpg|thumb|150px|Members of the 2007 IMO Greek team]]
 
[[Image:Perfect-scorers.jpg|thumb|right|alt=Four men in black suits with bluish-white dress shirts and brightly-coloured ties standing in front of a wall composed of wooden panels.|The four perfect scorers in the 2001 IMO. From left to right: [[Gabriel Carroll]], [[Reid Barton]] (both United States), Liang Xiao and Zhiqiang Zhang (both China).]]
[[File:Bdimoteam09.JPG|thumb|right|alt=Ten people facing forward, in two lines of five. In the front row are five boys in their late teens. Behind them are four adults, and one person who appears to be in his late teens.|The Bangladesh team at the 2009 IMO]] 
[[File:Matematička gimnazija - Mathematical Gymnasium Belgrade - MGB - IMO 2010 - pic3.jpg|thumb|right|alt=Six boys, standing on a line, all wearing white tops with red logos on their chest. They are holding a red, blue and white striped flag, which features a prominent crown and coat of arms.|Serbia's team for the 2010 IMO]]
[[File:Zhuo Qun (Alex) Song.jpg|thumb|[[Song Zhuo Qun|Zhuo Qun (Alex) Song]] (Canadian), the most highly decorated IMO contestant with 5 golds and 1 bronze medal]]
[[File:Maryam_Mirzakhani_in_Seoul_2014.jpg|thumb|[[Maryam Mirzakhani]] (Iran), the first woman to be honored with a [[Fields Medal]], won 2 gold medals in 1994 and 1995, getting a perfect score in the second year.]]
{| class="wikitable sortable plainrowheaders" 
!scope=col| 
!scope=col| Venue
!scope=col| Year
!class="unsortable" scope=col| Date
!scope=col| Top-ranked country<ref name=results>{{Cite web|url=https://www.imo-official.org/results.aspx|title=Ranking of countries|publisher=International Mathematical Olympiad|access-date=2011-06-20}}</ref>
!class="unsortable" scope=col| Refs
|-
|align=right| 1&nbsp;
!scope=row|{{flagicon|Romania|1952}} [[Brașov]] and [[Bucharest]]
|align=center|1959 ||July 21–31<ref name=imo1959>{{cite web |url=https://www.imo-official.org/year_individual_r.aspx?year=1959&column=total&order=desc |title=1st IMO 1959 |publisher=International Mathematical Olympiad |accessdate=2022-07-17}}</ref> ||{{flagu|Romania|1952}}
|align=center|<ref name="lord">{{cite web|url=http://amc.maa.org/e-exams/e9-imo/imoteamrecord.shtml|archive-url=https://web.archive.org/web/20091128021212/http://amc.maa.org/e-exams/e9-imo/imoteamrecord.shtml|url-status=dead|archive-date=2009-11-28|title=Historical Record of US Teams|publisher=[[Mathematical Association of America]]|access-date=2011-06-19}}</ref>
|-
|align=right| 2&nbsp;
!scope=row|{{flagicon|Romania|1952}} [[Sinaia]]
|align=center|1960 ||July 18–26 ||{{flagu|Czechoslovakia}}
|align=center|<ref name="lord"/>
|-
|align=right| 3&nbsp; 
!scope=row|{{flagicon|Hungary}} [[Veszprém]]
|align=center|1961 ||July 6–16 || rowspan="2" |{{flagu|Hungary}}
|align=center|<ref name="lord"/>
|-
|align=right|4&nbsp;
!scope=row|{{flagicon|Czechoslovakia}} {{sort|Ceske|[[České Budějovice]]}}
|align=center| 1962 ||July 7–15 
|align=center|<ref name="lord"/>
|-
|align=right|5&nbsp;
!scope=row|{{flagicon|Poland}} [[Warsaw]] and [[Wrocław]]
|align=center|1963 ||July 5–13 || rowspan="5" |{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|6&nbsp;
!scope=row|{{flagicon|Soviet Union}} [[Moscow]]
|align=center|1964 ||June 30 – July 10 
|align=center|<ref name="lord"/>
|-
|align=right|7&nbsp;
!scope=row|{{flagicon|East Germany}} [[East Berlin]]
|align=center|1965 ||July 3–13 
|align=center|<ref name="lord"/>
|-
|align=right|8&nbsp;
!scope=row|{{flagicon|Bulgaria|1946}} [[Sofia]]
|align=center|1966 ||July 1–14 
|align=center|<ref name="lord"/>
|-
|align=right|9&nbsp;
!scope=row|{{flagicon|Yugoslavia}} [[Cetinje]]
|align=center|1967 ||July 2–13 
|align=center|<ref name="lord"/>
|-
|align=right|10&nbsp;
!scope=row|{{flagicon|Soviet Union}} [[Moscow]]
|align=center|1968 ||July 5–18 ||{{flagu|East Germany}}
|align=center|<ref name="lord"/>
|-
|align=right|11&nbsp;
!scope=row|{{flagicon|Romania|1965}} [[Bucharest]]
|align=center|1969 ||July 5–20 || rowspan="3" |{{flagu|Hungary}}
|align=center|<ref name="lord"/>
|-
|align=right|12&nbsp;
!scope=row|{{flagicon|Hungary}} [[Keszthely]]
|align=center|1970 ||July 8–22 
|align=center|<ref name="lord"/>
|-
|align=right|13&nbsp;
!scope=row|{{flagicon|Czechoslovakia}} [[Žilina]]
|align=center|1971 ||July 10–21 
|align=center|<ref name="lord"/>
|-
|align=right|14&nbsp;
!scope=row|{{flagicon|Poland}} [[Toruń]]
|align=center|1972 ||July 5–17 || rowspan="3" |{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|15&nbsp;
!scope=row|{{flagicon|Soviet Union}} [[Moscow]]
|align=center|1973 ||July 5–16 
|align=center|<ref name="lord"/>
|-
|align=right|16&nbsp;
!scope=row|{{flagicon|East Germany}} [[Erfurt]] and [[East Berlin]]
|align=center|1974 ||July 4–17 
|align=center|<ref name="lord"/>
|-
|align=right|17&nbsp;
!scope=row|{{flagicon|Bulgaria|1971}} [[Burgas]] and [[Sofia]]
|align=center|1975 ||July 3–16 ||{{flagu|Hungary}}
|align=center|<ref name="lord"/>
|- 
|align=right|18&nbsp;
!scope=row|{{flagicon|Austria}} [[Lienz]]
|align=center|1976 ||July 7–21 ||{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|19&nbsp;
!scope=row|{{flagicon|Yugoslavia}} [[Belgrade]]
|align=center|1977 ||July 1–13 ||{{flagu|United States}}
|align=center|<ref name="lord"/>
|-
|align=right|20&nbsp;
!scope=row|{{flagicon|Romania|1965}} [[Bucharest]]
|align=center|1978 ||July 3–10 ||{{flagu|Romania|1965}}
|align=center|<ref name="lord"/>
|-
|align=right|21&nbsp;
!scope=row|{{flagicon|United Kingdom}} [[London]]
|align=center|1979 ||June 30 – July 9 ||{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|{{sort|21.5|&nbsp;}}
!scope=row colspan=5|{{sort|1980|The 1980 IMO was due to be held in Mongolia. It was cancelled, and split into two unofficial events in Europe.}}<ref name=Mongolia>Unofficial events were held in Finland and Luxembourg in 1980. {{Cite web|url=http://www.imo-register.org.uk/#1980|title=UK IMO register|publisher=IMO register|access-date=2011-06-17}}</ref>
|-
|align=right|22&nbsp;
!scope=row|{{flagicon|United States}} [[Washington, D.C.]]
|align=center|1981 ||July 8–20 ||{{flagu|United States}}
| align=center |<ref name="lord"/>
|-
|align=right|23&nbsp;
!scope=row|{{flagicon|Hungary}} [[Budapest]]
|align=center|1982 ||July 5–14 || rowspan="2" |{{flagu|West Germany}}
|align=center|<ref name="lord"/>
|-
|align=right|24&nbsp;
!scope=row|{{flagicon|France}} [[Paris]]
|align=center|1983 ||July 1–12 
|align=center|<ref name="lord"/>
|-
|align=right|25&nbsp;
!scope=row|{{flagicon|Czechoslovakia}} [[Prague]]
|align=center|1984 ||June 29 – July 10 ||{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|26&nbsp;
!scope=row|{{flagicon|Finland}} [[Joutsa]]
|align=center|1985 ||June 29 – July 11 ||{{flagu|Romania|1965}}
|align=center|<ref name="lord"/>
|-
|align=right|27&nbsp;
!scope=row|{{flagicon|Poland}} [[Warsaw]]
|align=center|1986 ||July 4–15 ||{{flagu|Soviet Union}}<br>{{flagu|United States}}
|align=center|<ref name="lord"/>
|-
|align=right|28&nbsp;
!scope=row|{{flagicon|Cuba}} [[Havana]]
|align=center|1987 ||July 5–16 ||{{flagu|Romania|1965}}
|align=center|<ref name="lord"/>
|-
|align=right|29&nbsp; 
!scope=row|{{flagicon|Australia}} [[Sydney]] and [[Canberra]]
|align=center|1988 ||July 9–21 ||{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|30&nbsp;
!scope=row|{{flagicon|West Germany}} [[Braunschweig]]
|align=center|1989 ||July 13–24 || rowspan="2" |{{flagu|China}}
|align=center|<ref name="lord"/>
|-
|align=right|31&nbsp;
!scope=row|{{flagicon|China}} [[Beijing]]
|align=center|1990 ||July 8–19 
|align=center|<ref name="lord"/>
|-
|align=right|32&nbsp;
!scope=row|{{flagicon|Sweden}} [[Sigtuna]]
|align=center|1991 ||July 12–23 ||{{flagu|Soviet Union}}
|align=center|<ref name="lord"/>
|-
|align=right|33&nbsp;
!scope=row|{{flagicon|Russia|1991}} [[Moscow]]
|align=center|1992 ||July 10–21 || rowspan="2" |{{flagu|China}}
|align=center|<ref name="lord"/>
|-
|align=right|34&nbsp;
!scope=row|{{flagicon|Turkey}} [[Istanbul]]
|align=center|1993 ||July 13–24 
|align=center|<ref name="lord"/>
|-
|align=right|35&nbsp;
!scope=row|{{flagicon|Hong Kong|1959}} [[British Hong Kong|Hong Kong]]
|align=center|1994 ||July 8–20 ||{{flagu|United States}}
|align=center|<ref name="lord"/>
|-
|align=right|36&nbsp;
!scope=row|{{flagicon|Canada}} [[Toronto]]
|align=center|1995 ||July 13–25 ||{{flagu|China}}
|align=center| <ref>{{cite web|url=http://imo.math.ca/IMO95/|title=IMO 1995|access-date=2008-03-17|publisher=Canadian Mathematical Society|url-status=dead|archive-url=https://web.archive.org/web/20080229050644/http://imo.math.ca/IMO95/|archive-date=2008-02-29}}</ref>
|-
|align=right|37&nbsp;
!scope=row|{{flagicon|India}} [[Mumbai]]
|align=center|1996 ||July 5–17 ||{{flagu|Romania}}
|align=center| <ref>{{cite web|url=http://imo.math.ca/IMO96/|title=IMO 1996|access-date=2008-03-17|publisher=Canadian Mathematical Society|url-status=dead|archive-url=https://web.archive.org/web/20080223074256/http://imo.math.ca/IMO96/|archive-date=2008-02-23}}</ref>
|-
|align=right|38&nbsp;
!scope=row|{{flagicon|Argentina}} [[Mar del Plata]]
|align=center|1997 ||July 18–31 ||{{flagu|China}}
|align=center| <ref>{{cite web|url=https://oma.org.ar/imo97/|title=IMO 1997|access-date=2008-03-17|publisher=Argentina|language=es}}</ref>
|-
|align=right|39&nbsp;
!scope=row|{{flagicon|Taiwan}} [[Taipei]]
|align=center|1998 ||July 10–21 ||{{flagu|Iran}}
|align=center| <ref>{{cite web|url=http://imo.math.ntnu.edu.tw/|title=IMO 1998|publisher=Republic of China|archive-url=https://web.archive.org/web/19981205203518/http://imo.math.ntnu.edu.tw/|archive-date=1998-12-05|url-status=dead}}</ref>
|-
|align=right|40&nbsp;
!scope=row|{{flagicon|Romania}} [[Bucharest]]
|align=center|1999 ||July 10–22 ||{{flagu|China}}<br>{{flagu|Russia}}
|align=center| <ref>{{cite web|url=http://imo.math.ca/IMO99/|title=IMO 1999|access-date=2008-03-17|publisher=Canadian Mathematical Society|url-status=dead|archive-url=https://web.archive.org/web/20080223162939/http://imo.math.ca/IMO99/|archive-date=2008-02-23}}</ref>
|-
|align=right|41&nbsp;
!scope=row|{{flagicon|South Korea}} [[Daejeon]]
|align=center|2000 ||July 13–25 || rowspan="3" |{{flagu|China}}
|align=center| <ref>{{cite web|url=http://imo.wolfram.com/|title=IMO 2000|access-date=2008-03-17|publisher=Wolfram}}</ref>
|-
|align=right|42&nbsp;
!scope=row|{{flagicon|United States}} [[Washington, D.C.]]
|align=center|2001 ||July 1–14 
|align=center| <ref>{{cite web|url=http://imo.math.ca/IMO2001/|title=IMO 2001|access-date=2008-03-17|publisher=Canadian Mathematical Society|url-status=dead|archive-url=https://web.archive.org/web/20110518105614/http://imo.math.ca/IMO2001/|archive-date=2011-05-18}}</ref>
|-
|align=right|43&nbsp;
!scope=row|{{flagicon|United Kingdom}} [[Glasgow]]
|align=center|2002 ||July 19–30 
|align=center| <ref>{{Cite book|last=Andreescu|first=Titu|title=USA & International Mathematical Olympiads 2002|isbn=978-0-88385-815-8|year=2004|publisher=Mathematical Association of America}}</ref>
|-
|align=right|44&nbsp;
!scope=row|{{flagicon|Japan}} [[Tokyo]]
|align=center|2003 ||July 7–19 ||{{flagu|Bulgaria}}
|align=center| <ref>{{cite web|url=http://www.imo2003.com/|title=IMO 2003|access-date=2008-03-17|publisher=Japan|url-status=dead|archive-url=https://web.archive.org/web/20080306061006/http://www.imo2003.com/|archive-date=2008-03-06}}</ref>
|-
|align=right|45&nbsp;
!scope=row|{{flagicon|Greece}} [[Athens]]
|align=center|2004 ||July 6–18 || rowspan="3" |{{flagu|China}}
|align=center| <ref>{{cite web|url=http://www.imo2004.gr/|title=IMO 2004|publisher=Greece|archive-date=2004-06-27|archive-url=https://web.archive.org/web/20040627033941/http://www.imo2004.gr/|url-status=dead}}</ref>
|-
|align=right|46&nbsp;
!scope=row|{{flagicon|Mexico}} [[Mérida, Yucatán|Mérida]]
|align=center|2005 ||July 8–19 
|align=center| <ref>{{cite web|url=http://erdos.fciencias.unam.mx/|title=IMO 2005|publisher=Mexico|archive-url=https://web.archive.org/web/20050711000638/http://erdos.fciencias.unam.mx/|archive-date=2005-07-11|url-status=dead}}</ref>
|-
|align=right|47&nbsp;
!scope=row|{{flagicon|Slovenia}} [[Ljubljana]]
|align=center|2006 ||July 6–18 
|align=center| <ref>{{cite web|url=http://www.imo2006.dmfa.si/|title=IMO 2006|access-date=2008-03-17|publisher=Slovenia|archive-url=https://web.archive.org/web/20090228152032/http://imo2006.dmfa.si/|archive-date=2009-02-28}}</ref>
|-
|align=right|48&nbsp;
!scope=row|{{flagicon|Vietnam}} [[Hanoi]]
|align=center|2007 ||July 19–31 ||{{flagu|Russia}}
|align=center| <ref>{{cite web|url=http://www.imo2007.edu.vn/|title=IMO 2007|access-date=2008-03-17|publisher=Vietnam|archive-url=https://web.archive.org/web/20090212162859/http://imo2007.edu.vn/|archive-date=2009-02-12}}</ref>
|-
|align=right|49&nbsp;
!scope=row|{{flagicon|Spain}} [[Madrid]]
|align=center|2008 ||July 10–22 || rowspan="4" |{{flagu|China}}
|align=center| <ref>{{cite web|url=http://www.imo-2008.es/|title=IMO 2008|access-date=2008-03-17|publisher=Spain|archive-date=26 February 2008|archive-url=https://web.archive.org/web/20080226125002/http://www.imo-2008.es/|url-status=dead}}</ref>
|-
|align=right|50&nbsp;
!scope=row|{{flagicon|Germany}} [[Bremen]]
|align=center|2009 ||July 10–22 
|align=center| <ref>{{cite web|url=http://www.imo2009.de/|title=IMO 2009|access-date=2008-03-17|publisher=Germany|language=de}}</ref>
|-
|align=right|51&nbsp;
!scope=row|{{flagicon|Kazakhstan}} [[Astana]]
|align=center|2010 ||July 2–14 
|align=center| <ref>{{Cite web|url=https://www.imo-official.org/year_info.aspx?year=2010|title=51st IMO 2010|publisher=IMO|access-date=2011-07-22}}</ref>
|-
|align=right|52&nbsp;
!scope=row|{{flagicon|Netherlands}} [[Amsterdam]]
|align=center|2011 ||July 12–24 
|align=center| <ref>{{Cite web|url=https://www.imo-official.org/year_info.aspx?year=2011|title=52nd IMO 2011|publisher=IMO|access-date=2011-07-22}}</ref>
|-
|align=right|53&nbsp;
!scope=row|{{flagicon|Argentina}} [[Mar del Plata]]
|align=center|2012 ||July 4–16 ||{{flagu|South Korea}}
|align=center| <ref>{{Cite web|url=https://www.imo-official.org/year_info.aspx?year=2012|title=53rd IMO 2012|publisher=IMO|access-date=2011-07-22}}</ref>
|-
|align=right|54&nbsp;
!scope=row|{{flagicon|COL}} [[Santa Marta]] 
|align=center|2013 ||July 18–28 || rowspan="2" |{{flagu|China}}
|align=center| <ref>{{cite web |title=54th International Mathematical Olympiad |url=http://www.uan.edu.co/imo2013/en/ |publisher=Universidad Antonio Nariño |access-date=July 20, 2012 |url-status=dead |archive-url=https://web.archive.org/web/20130121125749/http://www.uan.edu.co/imo2013/en/ |archive-date=January 21, 2013 }}</ref>
|-
|align=right|55&nbsp;
!scope=row|{{flagicon|RSA}} [[Cape Town]]
|align=center|2014 || July 3–13 
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2014|title=55th IMO 2014|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|56&nbsp;
!scope=row|{{flagicon|THA}} [[Chiang Mai Province|Chiang Mai]]
|align=center|2015 || July 4–16 || rowspan="2" | {{flagu|United States}}
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2015|title=56th IMO 2015|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|57&nbsp;
!scope=row|{{flagicon|HKG}} [[Hong Kong]]
|align=center|2016 || July 6–16 
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2016|title=57th IMO 2016|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|58&nbsp;
!scope=row|{{flagicon|BRA}} [[Rio de Janeiro]] 
|align=center|2017 || July 12–23 || {{flagu|South Korea}}
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2017|title=58th IMO 2017|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|59&nbsp;
!scope=row|{{flagicon|ROM}} [[Cluj-Napoca]]
|align=center|2018 || July 3–14 || {{flagu|United States}}
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2018|title=59th IMO 2018|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|60&nbsp;
!scope=row|{{flagicon|GBR}} [[Bath, Somerset|Bath]]
|align=center|2019 || July 11–22 || {{flagu|China}}<br>{{flagu|United States}}
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2019|title=60th IMO 2019|publisher=IMO|access-date=2016-09-10}}</ref>
|-
|align=right|61&nbsp;
!scope=row|{{flagicon|RUS}} [[Saint Petersburg]] (virtual)
|align=center|2020 || September 19–28 || rowspan="4" |{{flagu|China}}
|align=center| <ref>Becomes a virtual event due to [[COVID-19 pandemic]].</ref><ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2020|title=61st IMO 2020|publisher=IMO|access-date=2016-09-10}}</ref><ref>{{cite web|url=https://imo2020.ru/|title=61st IMO 2020|access-date=2018-12-25}}</ref><ref>{{Cite web|url=https://imo2020.ru/wp-content/uploads/2020/04/Annual-Regulations-for-IMO-2020_Aprilrevised.pdf|title=Annual Regulations for IMO 2020|website=Imo2020.ru|access-date=8 November 2021}}</ref>
|-
|align=right|62&nbsp;
!scope=row|{{flagicon|RUS}} [[Saint Petersburg]] (virtual)
|align=center|2021 || July 7–17 
|align=center|<ref>{{cite web|url=https://www.imo-official.org/year_country_r.aspx?year=2021|title=62nd IMO 2021 Result Table|website=Imo-official.org|access-date=2021-11-08}}</ref>{{refn|IMO 2021 was originally to be held in Washington D.C., US, but the US was forced to give up hosting soon after the start of the COVID-19 pandemic, which caused funding problems. Russia agreed to host for the second time in a row.<ref name="virtual2020">{{cite web|url=https://imof.co/virtual-imo2020-in-st-petersburg/|title=Virtual IMO 2020 – Russia|website= International Mathematical Olympiad Foundation|date=2020-07-11|access-date=2023-08-22}}</ref>|group=n}}
|-
|align=right|63&nbsp;
!scope=row|{{flagicon|Norway}} [[Oslo]]
|align=center|2022 || July 6–16
|align=center|<ref>{{cite web|url=https://www.imo-official.org/year_country_r.aspx?year=2022|title=63rd IMO 2022 Result Table|website=Imo-official.org|access-date=2022-07-14}}</ref>
|-
|align=right|64&nbsp;
!scope=row|{{flagicon|Japan}} [[Chiba Prefecture|Chiba]]
|align=center|2023 || July 2–13
|align=center|<ref>{{cite web|url=https://www.imo-official.org/year_country_r.aspx?year=2023|title=64th IMO 2023 Result Table|publisher=IMO|access-date=2019-07-22}}</ref>
|-
|align=right|65&nbsp;
!scope=row|{{flagicon|GBR}} [[Bath, Somerset|Bath]]
|align=center|2024 || July 11–22|| {{flagu|United States}}
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2024|title=65th IMO 2024|publisher=IMO|access-date=2021-07-17}}</ref><ref>{{Cite web |title=International Mathematical Olympiad 2024 |url=https://www.imo2024.uk/ |archive-url=https://web.archive.org/web/20220608101016/https://www.imo2024.uk/ |url-status=dead |archive-date=2022-06-08 |access-date=2022-06-11 |website=www.imo2024.uk}}</ref>{{refn|group=n|name=IMO2024 Original Location|The originally determined location for hosting IMO 2024 was [[Ukraine]]. Due to the [[Russian invasion of Ukraine|recent conflicts between the country and Russia]], the location was changed to Bath, in which IMO 2019 was hosted.<ref>{{cite web|url=https://www.imo2024.uk|title=IMO 2024|publisher=IMO|access-date=2023-07-12}}</ref>}}
|-
|align=right|66&nbsp;
!scope=row|{{flagicon|Australia}} [[Sunshine Coast, Queensland|Sunshine Coast]]
|align=center|2025 || July 10–20||{{flagu|China}}
|align=center| <ref>{{Cite web |title=66th IMO 2025 |url=https://www.imo-official.org/year_country_r.aspx?year=2025 |access-date=18 July 2025 |website=International Mathematical Olympiad}}</ref><ref>{{cite web|url=https://www.amt.edu.au/news/the-nations-newest-olympians-were-revealed-today-with-high-hopes-for-medals-on-the-international-stage|title=THE NATION'S NEWEST OLYMPIANS WERE REVEALED TODAY WITH HIGH HOPES FOR MEDALS ON THE INTERNATIONAL STAGE
|publisher=Australian Maths Trust|access-date=2024-07-11}}</ref>
|-
|align=right|67&nbsp;
!scope=row|{{flagicon|China}} [[Shanghai]]
|align=center|2026 || July 10–20||
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2026|title=67th IMO 2026|publisher=IMO|access-date=2023-07-11}}</ref>
|-
|align=right|68&nbsp;
!scope=row|{{flagicon|Hungary}} (TBA)
|align=center|2027 || ||
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2027|title=68th IMO 2027|publisher=IMO|access-date=2024-01-07}}</ref>
|-
|align=right|69&nbsp;
!scope=row|{{flagicon|Saudi Arabia}} (TBA)
|align=center|2028 || ||
|align=center| <ref>{{cite web|url=https://www.imo-official.org/year_info.aspx?year=2028|title=69th IMO 2028|publisher=IMO|access-date=2024-08-25}}</ref>
|-
|align=right|70&nbsp;
!scope=row|{{flagicon|Mongolia}} [[Ulaanbaatar]]
|align=center|2029 || ||
|align=center| <ref>{{cite web|url=https://akipress.com/news:839433:Mongolia_to_host_70th_International_Mathematical_Olympiad_in_2029/|title=70th IMO 2029|publisher=AKI Press|access-date=2025-07-14}}</ref>
|}

==Notable achievements==
===National===
The following nations have achieved the highest team score in the respective competition:

* China, 25 times: in 1989, 1990, 1992, 1993, 1995, 1997, 1999 (joint), 2000–2002, 2004–2006, 2008–2011, 2013, 2014, 2019 (joint), 2020–2023, 2025;<ref name=":0">{{Cite web |title=International Mathematical Olympiad – People's Republic of China – Team Results |url=https://www.imo-official.org/country_team_r.aspx?code=CHN |access-date=2023-07-12 |website=www.imo-official.org}}</ref>
* Russia (including [[Soviet Union]]), 16 times: in 1963–1967, 1972–1974, 1976, 1979, 1984, 1986 (joint), 1988, 1991, 1999 (joint), 2007;<ref name=rus/><ref name=ussr>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=USS|title=International Mathematical Olympiad – Union of Soviet Socialist Republics – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* United States, 9 times: in 1977, 1981, 1986 (joint), 1994, 2015, 2016, 2018, 2019 (joint), 2024;<ref name=usa/>
* Hungary, 6 times: in 1961, 1962, 1969–1971, 1975;<ref name=hun>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=HUN|title=International Mathematical Olympiad – Hungary – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* Romania, 5 times: in 1959, 1978, 1985, 1987, 1996;<ref name=rou>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=ROU|title=International Mathematical Olympiad – Romania – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* West Germany, twice: in 1982 and 1983;<ref name=ger>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=GER|title=International Mathematical Olympiad – Germany – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* South Korea, twice: in 2012 and 2017;<ref name=rok/>
* Bulgaria, once: in 2003;<ref>{{cite web|url=http://www.mmjp.or.jp/jmo/imo2003/contents/results_all.txt|title=Results of the 44th International Mathematical Olympiad|website=Mmjp.or.jp|access-date=2008-03-05|archive-date=2 May 2008|archive-url=https://web.archive.org/web/20080502185609/http://www.mmjp.or.jp/jmo/imo2003/contents/results_all.txt|url-status=dead}}</ref>
* Iran, once: in 1998;<ref name=irn>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=GDR|title=International Mathematical Olympiad – Islamic Republic of Iran – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* East Germany, once: in 1968.<ref name=gdr>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=GDR|title=International Mathematical Olympiad – German Democratic Republic – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>

The following nations have achieved an all-members-gold IMO with a full team:

* China, 16 times: in 1992, 1993, 1997, 2000–2002, 2004, 2006, 2009–2011, 2019, 2021–2023, 2025.<ref name=":0" />
* United States, 4 times: in 1994, 2011, 2016, and 2019.<ref name=usa>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=USA|title=International Mathematical Olympiad – United States of America – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* South Korea, 3 times: in 2012, 2017, and 2019.<ref name=rok>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=KOR|title=International Mathematical Olympiad – Republic of Korea – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* Russia, twice: in 2002 and 2008.<ref name=rus>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=RUS|title=International Mathematical Olympiad – Russian Federation – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>
* Bulgaria, once: in 2003.<ref>{{Cite web|url=https://www.imo-official.org/country_team_r.aspx?code=BGR|title=International Mathematical Olympiad – Bulgaria – Team Results|website=Imo-official.org|access-date=8 November 2021}}</ref>

The only countries to have their entire team score perfectly in the IMO were the United States in 1994, China in 2022, and Luxembourg, whose 1-member team had a perfect score in 1981. The US's success earned a mention in ''[[TIME Magazine]]''.<ref>{{cite magazine|url=https://content.time.com/time/magazine/article/0,9171,981185,00.html|title=No. 1 and Counting|access-date=2010-02-23 | magazine=Time | date=1994-08-01}}</ref> Hungary won IMO 1975 in an unorthodox way when none of the eight team members received a gold medal (five silver, three bronze).<ref name=hun/> The second-place team, East Germany, also did not have a single gold medal winner (four silver, four bronze).<ref name=gdr/>

The current ten countries with the best all-time results are as follows:<ref>{{cite web|url=https://www.imo-official.org/results_country.aspx?column=awards&order=asc|title=Results: Cumulative Results by Country|website=Imo-official.org|access-date=2023-07-29}}</ref>

{{Static row numbers}}
{| class="wikitable sortable static-row-numbers" 
! Country !! Appearances !! Gold !! Silver !! Bronze !! Honorable mentions 
|-
| align=left|  {{flag|China}} ||align=center| 39 ||align=center| 185 ||align=center| 37 ||align=center| 6  ||align=center| 0
|-
| align=left|  {{flag|United States}} || align=center|50 ||align=center| 151 ||align=center| 120 ||align=center| 30 ||align=center| 1
|-
| align=left| {{flag|Russia}} ||align=center| 30 || align="center" | 106
| align="center" | 62 || align="center" | 12 ||align=center| 0 
|-
| align=left| {{flag|South Korea}} ||align=center| 37 ||align=center| 95 ||align=center| 83 ||align=center| 28  ||align=center| 7 
|-
| align=left| {{flag|Hungary}} ||align=center| 64 ||align=center| 88 ||align=center| 174 ||align=center| 116 ||align=center| 10 
|-
| align=left| {{flag|Romania}} ||align=center| 65 ||align=center| 86 ||align=center| 158 ||align=center| 111 ||align=center| 7
|- style=background:#bbb
| align=left| {{flag|Soviet Union}}{{#tag:ref|The Soviet Union participated the IMO for the last time in 1991 due to the [[Dissolution of the Soviet Union]]. From 1992, former Soviet countries – including Russia – entered separately.<ref name=results/>|group=n}} ||align=center| 29 ||align=center| 77 ||align=center| 67 ||align=center| 45 ||align=center| 0 
|-
| align=left| {{flag|Vietnam}} ||align=center| 48 ||align=center| 69 ||align=center| 117 ||align=center| 85 ||align=center| 3
|-
| align=left| {{flag|Bulgaria}} ||align=center| 65 ||align=center| 57 ||align=center| 130 ||align=center| 121 ||align=center| 15
|-
| align=left| {{flag|United Kingdom}} ||align=center| 57 ||align=center| 56 ||align=center| 124 ||align=center| 131 ||align=center| 18 
|}

===Individual===
{{see also|List of International Mathematical Olympiad participants}}
Several individuals have consistently scored highly and/or earned medals on the IMO: [[Zhuo Qun Song]] (Canada) is the most highly decorated participant<ref>{{cite web|url=https://www.imo-official.org/hall.aspx |title=International Mathematical Olympiad Hall of Fame |publisher=Imo-official.org |access-date=2015-07-15}}</ref> with five gold medals (including one perfect score in 2015) and one bronze medal.<ref>{{cite web|url=https://www.imo-official.org/participant_r.aspx?id=19624 |title=IMO Official Record for Zhuo Qun (Alex) Song |publisher=Imo-official.org |access-date=2015-07-15}}</ref> [[Reid W. Barton|Reid Barton]] (United States) was the first participant to win a gold medal four times (1998–2001).<ref>{{cite journal|url=http://www.sciencemag.org/cgi/content/summary/293/5530/597|title=IMO's Golden Boy Makes Perfection Look Easy|access-date=2008-03-05 | doi=10.1126/science.293.5530.597|pmid=11474084|volume=293|issue=5530|journal=Science|page=597|year=2001|last1=MacKenzie|first1=D.|s2cid=8587484|url-access=subscription}}</ref> Barton is also one of only eight four-time [[William Lowell Putnam Mathematical Competition#Putnam Fellows|Putnam Fellow]]s (2001–04). [[Christian Reiher]] (Germany), [[Lisa Sauermann]] (Germany), {{ill|Teodor von Burg|sr|Теодор фон Бург}} (Serbia), Nipun Pitimanaaree (Thailand) and Luke Robitaille (United States) are the only other participants to have won four gold medals (2000–03, 2008–11, 2009–12, 2010–13, 2011–14, and 2019–22 respectively); Reiher also received a bronze medal (1999), Sauermann a silver medal (2007), von Burg a silver medal (2008) and a bronze medal (2007), and Pitimanaaree a silver medal (2009).<ref>{{cite web|url=https://www.imo-official.org/hall.aspx|title=International Mathematical Olympiad Hall of Fame|access-date=2009-07-18}}</ref> Wolfgang Burmeister (East Germany), Martin Härterich (West Germany), Iurie Boreico (Moldova), and Lim Jeck (Singapore) are the only other participants besides Reiher, Sauermann, von Burg, and Pitimanaaree to win five medals with at least three of them gold.<ref name="more">{{cite web|url=https://www.imo-register.org.uk/2017-report.pdf|title=Geoff Smith (August 2017). "UK IMO team leader's report". University of Bath. |access-date=2018-07-02}}</ref> [[Ciprian Manolescu]] (Romania) managed to write a perfect paper (42 points) for gold medal more times than anybody else in the history of the competition, doing it all three times he participated in the IMO (1995, 1996, 1997).<ref>{{cite web|url=http://www.unl.edu/amc/e-exams/e9-imo/imoteamrecord.shtml|title=IMO team record|access-date=2008-03-05|archive-url=https://web.archive.org/web/20080220172111/http://www.unl.edu/amc/e-exams/e9-imo/imoteamrecord.shtml|archive-date=2008-02-20|url-status=dead}}</ref> Manolescu is also a three-time Putnam Fellow (1997, 1998, 2000).<ref name="putnam">{{cite web|url=http://www.maa.org/awards/putnam.html|archive-url=https://web.archive.org/web/20000229230334/http://www.maa.org/awards/putnam.html|url-status=dead|archive-date=2000-02-29|title=The Mathematical Association of America's William Lowell Putnam Competition|access-date=2008-03-05}}</ref> [[Eugenia Malinnikova]] ([[Soviet Union]]) is the highest-scoring female contestant in IMO history. She has 3 gold medals in IMO 1989 (41 points), IMO 1990 (42) and IMO 1991 (42), missing only 1 point in 1989 to precede Manolescu's achievement.<ref>{{Harv|Vakil|1997}}</ref>

[[Terence Tao]] (Australia) participated in IMO 1986, 1987 and 1988, winning bronze, silver and gold medals respectively. He won a gold medal when he just turned thirteen in IMO 1988, becoming the youngest person<ref>{{cite web|url=http://www.iht.com/articles/2007/03/13/news/math.php|title=A packed house for a math lecture? Must be Terence Tao|website=Iht.com|access-date=2008-03-05}}</ref> to receive a gold medal (Zhuo Qun Song of Canada also won a gold medal at age 13, in 2011, though he was older than Tao). Tao also holds the distinction of being the youngest medalist with his 1986 bronze medal, followed by 2009 bronze medalist [[Raúl Chávez Sarmiento]] (Peru), at the age of 10 and 11 respectively.<ref>{{Cite news |url=http://www.livinginperu.com/news/9641 |title=Peru won four silver and two bronze medals in International Math Olympiad |date=July 22, 2009 |website=Livinginperu.com }}</ref> Representing the United States, [[Noam Elkies]] won a gold medal with a perfect paper at the age of 14 in 1981. Both Elkies and Tao could have participated in the IMO multiple times following their success, but entered university and therefore became ineligible.

==Gender gap and the launch of European Girls' Mathematical Olympiad==
Over the years, since its inception to present, the IMO has attracted far more male contestants than female contestants.<ref>{{Cite web|last=Whitney|first=A. K.|date=2016-04-18|title=Why Does the Gender Gap Persist in International Math Competitions?|url=https://www.theatlantic.com/education/archive/2016/04/girls-math-international-competiton/478533/|access-date=2021-08-15|website=The Atlantic|language=en}}</ref><ref>{{Cite news|last=Loewus|first=Liana|date=2015-07-27|title=Gender Gaps at the Math Olympiad: Where Are the Girls?|url=https://www.edweek.org/teaching-learning/gender-gaps-at-the-math-olympiad-where-are-the-girls/2015/07|access-date=2021-08-15|website=Education Week|language=en}}</ref><ref>{{Cite news|url=https://www.ft.com/content/8d9dba28-ae17-11e9-b3e2-4fdf846f48f5 |archive-url=https://ghostarchive.org/archive/20221210/https://www.ft.com/content/8d9dba28-ae17-11e9-b3e2-4fdf846f48f5 |archive-date=10 December 2022 |url-access=subscription|title=The biggest gender divide is in mathematics|newspaper=[[Financial Times]]|date=5 September 2019|last1=Hoyos|first1=Carola}}</ref> During the period 2000–2021, there were only 1,102 female contestants (9.2%) out of a total of 11,950 contestants. The gap is even more significant in terms of IMO gold medallists; from 1959 to 2021, there were 43 female (3.3%) and 1295 male gold medal winners.<ref>{{Cite web|url=https://www.imo-official.org/hall.aspx?column=awards&order=desc&gender=filter&block=1&nameform=western|title = International Mathematical Olympiad|website=Imo-official.org}}</ref>

This gender gap in participation and in performance at the IMO level led to the establishment of the [[European Girls' Mathematical Olympiad]] (EGMO).<ref>{{Cite web|url=https://www.theguardian.com/science/2015/oct/13/mathematical-ratios-competition-girls-plus-or-minus|title=Mathematical ratios: Is a competition just for girls a plus or a minus?|website=[[TheGuardian.com]]|date=13 October 2015}}</ref>

==Media coverage==
* A documentary, "Hard Problems: The Road To The World's Toughest Math Contest" was made about the United States 2006 IMO team.<ref>[http://www.hardproblemsmovie.com/ ''Hard Problems: The Road to the World's Toughest Math Contest''] {{Webarchive|url=https://web.archive.org/web/20100715212537/http://www.hardproblemsmovie.com/ |date=2010-07-15 }}, Zala Films and the [[Mathematical Association of America]], 2008.</ref>
* A BBC documentary titled ''[[Beautiful Young Minds]]'' aired July 2007 about the IMO.
* A BBC fictional film titled ''[[X+Y]]'' released in September 2014 tells the story of an [[Autism spectrum|autistic]] boy who took part in the Olympiad.
* A book named ''Countdown'' by Steve Olson tells the story of the United States team's success in the 2001 Olympiad.<ref>{{Cite book|last=Olson|first=Steve|url=https://books.google.com/books?id=-ctkwbaws7gC|title=Count Down: Six Kids Vie for Glory at the World's Toughest Math Competition|date=2005|publisher=Houghton Mifflin Harcourt|isbn=978-0-618-56212-1|language=en}}</ref>

==See also==
*[[List of International Mathematical Olympiads]]
*[[International Mathematics Competition for University Students]] (IMC)
*[[International Science Olympiad]]
*[[List of mathematics competitions]]
*[[Pan-African Mathematics Olympiads]]
* [[Junior Science Talent Search Examination]]
*[[Art of Problem Solving]]
*[[Mathcounts]]

==Notes==
{{reflist|group=n}}

==Citations==
{{Reflist|30em}}

==References==
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==External links==
*[https://www.imo-official.org/ Official IMO web site]
*[https://web.archive.org/web/20040405065644/http://www.kalva.demon.co.uk/index.html Archive to the IMO 1959–2003 problems and solutions]
*[https://web.archive.org/web/20040328160450/http://www.imo.math.ca/ Old central IMO web site]

{{International mathematical activities}}
{{International Science Olympiad}}
{{Authority control}}
{{Good article}}

[[Category:International Mathematical Olympiad| ]]
[[Category:Recurring events established in 1959]]