List of International Mathematical Olympiads

The first of the International Mathematical Olympiads (IMOs) was held in Romania in 1959. The oldest of the International Science Olympiads, the IMO has since been held annually, except in 1980. That year, the competition initially planned to be held in Mongolia was cancelled due to the Soviet invasion of Afghanistan.^[1] Because the competition was initially founded for Eastern European countries participating in the Warsaw Pact, under the influence of the Eastern Bloc,^[2] the earlier IMOs were hosted only in Eastern European countries, gradually spreading to other nations.^[3] Sources differ about the cities hosting some of the early IMOs and the exact dates when they took place.^[4]^{[failed verification]}

The first IMO was held in Romania in 1959. Seven countries entered – Bulgaria, Czechoslovakia, East Germany, Hungary, Poland, Romania and the Soviet Union – with the hosts finishing as the top-ranked nation.^[5] The number of participating countries has since risen: 14 countries took part in 1969, 50 in 1989, and 104 in 2009.^[6]

North Korea is the only country whose entire team has been caught cheating, resulting in its disqualification at the 32nd IMO in 1991 and the 51st IMO in 2010.^[7] (However, the 2010 case was controversial.^[8]^[9]) There have been other disqualifications of contestants due to cheating, but such cases are not officially made public.^[10] In January 2011, Google gave €1 million to the IMO organization to help cover the costs of the events from 2011 to 2015.^[11]

List of Olympiads

The four perfect scorers in the 2001 IMO. From left to right: Gabriel Carroll, Reid Barton, Zhiqiang Zhang, and Liang Xiao.

#^[6]	Venue	Year	Date^[6]	Top-ranked country^[12]	References
1	Brașov and Bucharest	1959	June 23 – July 31	Romania	^[13]
2	Sinaia	1960	July 18 – July 25	Czechoslovakia	^[13]
3	Veszprém	1961	July 6 – July 16	Hungary	^[13]
4	České Budějovice	1962	July 7 – July 15	Hungary	^[13]
5	Warsaw and Wrocław	1963	July 5 – July 13	Soviet Union	^[13]
6	Moscow	1964	June 30 – July 10	Soviet Union	^[13]
7	East Berlin	1965	June 13 – July 13	Soviet Union	^[13]
8	Sofia	1966	July 3 – July 13	Soviet Union	^[13]
9	Cetinje	1967	July 7 – July 13	Soviet Union	^[13]
10	Moscow	1968	July 5 – July 18	East Germany	^[13]
11	Bucharest	1969	July 5 – July 20	Hungary	^[13]
12	Keszthely	1970	July 8 – July 22	Hungary	^[13]
13	Žilina	1971	July 10 – July 21	Hungary	^[13]
14	Toruń	1972	July 5 – July 17	Soviet Union	^[13]
15	Moscow	1973	July 5 – July 16	Soviet Union	^[13]
16	Erfurt and East Berlin	1974	July 4 – July 17	Soviet Union	^[13]
17	Burgas and Sofia	1975	July 3 – July 16	Hungary	^[13]
18	Lienz	1976	July 2 – July 21	Soviet Union	^[13]
19	Belgrade	1977	July 1 – July 13	United States	^[13]
20	Bucharest	1978	July 3 – July 10	Romania	^[13]
21	London	1979	June 30 – July 9	Soviet Union	^[13]
-	The 1980 IMO was due to be held in Mongolia. It was cancelled, and split into two unofficial events in Europe.^[1]
22	Washington, D.C.	1981	July 8 – July 20	United States	^[13]
23	Budapest	1982	July 5 – July 14	West Germany	^[13]
24	Paris	1983	July 3 – July 12	West Germany	^[13]
25	Prague	1984	June 29 – July 10	Soviet Union	^[13]
26	Joutsa	1985	June 29 – July 11	Romania	^[13]
27	Warsaw	1986	July 4 – July 15	Soviet Union United States	^[13]
28	Havana	1987	July 5 – July 16	Romania	^[13]
29	Sydney and Canberra	1988	July 9 – July 21	Soviet Union	^[13]
30	Braunschweig	1989	July 13 – July 24	China	^[13]
31	Beijing	1990	July 8 – July 19	China	^[13]
32	Sigtuna	1991	July 12 – July 23	Soviet Union	^[13]^{[n 1]}
33	Moscow	1992	July 10 – July 21	China	^[13]
34	Istanbul	1993	July 13 – July 24	China	^[13]
35	Hong Kong^{[n 2]}	1994	July 8 – July 20	United States	^[13]
36	Toronto	1995	July 13 – July 25	China	^[14]
37	Mumbai	1996	July 5 – July 17	Romania	^[15]
38	Mar del Plata	1997	July 18 – July 31	China	^[16]
39	Taipei	1998	July 10 – July 21	Iran	^[17]
40	Bucharest	1999	July 10 – July 22	China Russia	^[18]
41	Daejeon	2000	July 13 – July 25	China	^[19]
42	Washington, D.C.	2001	July 1 – July 14	China	^[20]
43	Glasgow	2002	July 19 – July 30	China	^[21]
44	Tokyo	2003	July 7 – July 19	Bulgaria	^[22]
45	Athens	2004	July 6 – July 18	China	^[23]
46	Mérida	2005	July 8 – July 19	China	^[24]
47	Ljubljana	2006	July 6 – July 18	China	^[25]
48	Hanoi	2007	July 19 – July 31	Russia	^[26]
49	Madrid	2008	July 10 – July 22	China	^[27]
50	Bremen	2009	July 10 – July 22	China	^[28]
51	Astana	2010	July 2 – July 14	China	^[29]
52	Amsterdam	2011	July 13 – July 24	China	^[30]
53	Mar del Plata	2012	July 4 – July 16	South Korea	^[31]
54	Santa Marta	2013	July 18 – July 28	China	^[32]
55	Cape Town	2014	July 3 – July 13	China	^[33]
56	Chiang Mai	2015	July 4 – July 16	United States	^[34]
57	Hong Kong	2016	July 6 – July 16	United States	^[35]
58	Rio de Janeiro	2017	July 12 – July 23	South Korea	^[36]
59	Cluj-Napoca	2018	July 3 – July 14	United States	^[37]
60	Bath	2019	July 11 – July 22	China United States	^[38]
61	St. Petersburg (online)^{[n 3]}^{[n 4]}	2020	September 19 – September 28	China	^[42]^[43]
62	St. Petersburg (online)^{[n 5]}^{[n 4]}	2021	July 14 – July 24	China	^[45]
63	Oslo (hybrid)	2022	July 6 – July 16	China	^[46]
64	Chiba	2023	July 2 – July 13	China	^[47]
65	Bath^{[n 6]}	2024	July 11 – July 22	TBD	^[49]
66	(TBA)	2025	TBD	TBD	^[50]
67	Shanghai	2026	TBD	TBD	^[51]
68	(TBA)	2027	TBD	TBD	^[52]