| AFG | Afghanistan | | | |
| ALB | Albania | Fatmir Hoxha | | |
| ALG | Algeria | | | |
| ARG | Argentina | Patricia Fauring | http://www.oma.org.ar/ | 1997 |
| ARM | Armenia | Garnik Tonoyan | | |
| AUS | Australia | Peter Taylor | http://www.amt.edu.au/ | 1988 |
| AUT | Austria | Robert Geretschläger | http://www.oemo.at/ | 1976 |
| AZE | Azerbaijan | Nazim Karimov | | |
| BAH | Bahrain | | | |
| BGD | Bangladesh | A A Munir Hasan | http://www.matholympiad.org.bd/ | |
| BLR | Belarus | Natalya Gorovaya | | |
| BEL | Belgium | Bart Windels | | |
| BEN | Benin | | | |
| BOL | Bolivia | Jorge Enriquez Cortez | | |
| BIH | Bosnia and Herzegovina | Muharem Avdispahić | | |
| BRA | Brazil | Nelly Carvajal | http://www.obm.org.br/ | |
| BRU | Brunei | | | |
| BGR | Bulgaria | Emil Milanov Kolev | http://www.math.bas.bg/bcmi/ | 1966, 1975 |
| KHM | Cambodia | Pheakdei Mauk | | |
| CMR | Cameroon | | | |
| CAN | Canada | Graham P. Wright | http://www.cms.math.ca/Olympiads/ | 1995 |
| CHI | Chile | Hernan Burgos | http://titan.usach.cl/~olimpiadas/ | |
| CHN | People's Republic of China | Zhu Fang | | 1990 |
| COL | Colombia | Maria Falk de Losada | http://olimpia.uan.edu.co | |
| CIS | Commonwealth of Independent States | | | |
| CRI | Costa Rica | Mario Marín Sánches | | |
| HRV | Croatia | Željko Hanjš | | |
| CUB | Cuba | Raúl Ochoa Rojas | | 1987 |
| CYP | Cyprus | Gregory Makrides | http://www.cms.org.cy | |
| CZE | Czech Republic | Jaroslav Švrček | http://www.math.muni.cz/~rvmo/ | |
| CZS | Czechoslovakia | | | 1962, 1971, 1984 |
| DEN | Denmark | Max Petersen | http://www.georgmohr.dk/ | |
| DOM | Dominican Republic | | | |
| ECU | Ecuador | Vicente Torres Álvarez | | |
| EST | Estonia | Jan Willemson | http://www.math.olympiaadid.ut.ee/ | |
| FIN | Finland | Matti Lehtinen | | 1985 |
| FRA | France | Claude Deschamps | http://www.animath.fr/ | 1983 |
| GEO | Georgia | Larry Gogoladze | | |
| GDR | German Democratic Republic | Hans-Dietrich Gronau | | 1965, 1974 |
| GER | Germany | Hans-Dietrich Gronau | http://www.mathematik-olympiaden.de/ | 1989, 2009 |
| HEL | Greece | Anargyros Fellouris | http://www.hms.gr | 2004 |
| GTM | Guatemala | Dorval Carías | | |
| HND | Honduras | | | |
| HKG | Hong Kong | Suk-Wan Chow | http://www.math.ust.hk/excalibur/ | 1994 |
| HUN | Hungary | József Pelikán | | 1961, 1970, 1982 |
| ISL | Iceland | Friđrik Diego | | |
| IND | India | Arvind Kumar | http://www.iisc.ernet.in/mocell/ | 1996 |
| IDN | Indonesia | Hery Susanto | | |
| IRN | Islamic Republic of Iran | Arash Rastegar | | |
| IRL | Ireland | Tom Laffey | http://www.ul.ie/~maths/imo.htm | |
| ISR | Israel | Shay Gueron | http://math2.haifa.ac.il/~israelmo/ | |
| ITA | Italy | Roberto Dvornicich | http://olimpiadi.dm.unipi.it/ | |
| JPN | Japan | Kozuaki Kobayashi | | 2003 |
| KAZ | Kazakhstan | Tildash Bituova | | 2010 |
| PRK | Democratic People's Republic of Korea | Ham Yong Chol | | |
| KOR | Republic of Korea | Dohan Kim | http://www.kms.or.kr | 2000 |
| KWT | Kuwait | Dr. Jasem Al-Besharah | | |
| KGZ | Kyrgyzstan | Boljiev Buras Asanbekovich | | |
| LVA | Latvia | Agnis Andžāns | http://www.liis.lv/NMS/ | |
| LIE | Liechtenstein | Daniel Sprecher | | |
| LTU | Lithuania | Kasuba Romualdas | | |
| LUX | Luxembourg | Charles Leytem | http://www.ltam.lu/math/math0.htm | |
| MAC | Macau | Ieng Tak Long | | |
| MKD | The Former Yugoslav Republic of Macedonia | Vesna Manova - Erakovik | | |
| MAS | Malaysia | M. Suhaimi Ramly | | |
| MLT | Malta | | | |
| MEX | Mexico | Radmila Bulajich Manfrino | http://www.omm.unam.mx/ | 2005 |
| MDA | Republic of Moldova | Ceapa Valentina | | |
| MNG | Mongolia | Dashdorj Ts | | |
| MNE | Montenegro | Božidar Šćepanović | | |
| MAR | Morocco | El Rhezzali Abdelmoumen - M. | | |
| MOZ | Mozambique | Luis de Nascimento Paulo | | |
| NLD | Netherlands | Quintijn Puite | http://wiskundeolympiade.nl/ | 2011 |
| NZL | New Zealand | Michael Albert | | |
| NIC | Nicaragua | | | |
| NGA | Nigeria | Steve Oluwaniyi | | |
| NOR | Norway | Øyvind Bakke | http://abelkonkurransen.no/ | |
| PAK | Pakistan | Alla Ditta Choudary | | |
| PAN | Panama | Pedro A. Marrone G. | http://olimpiada.tripod.com | |
| PAR | Paraguay | Gabriela Gómez Pasquali | http://www.omapa.org.py | |
| PER | Peru | Emilio Gonzaga Ramírez | | |
| PHI | Philippines | Ian June Garces | | |
| POL | Poland | Waldemar Pompe | http://www.mimuw.edu.pl/~chel/Olimp/olympiads.html | 1963, 1972, 1986 |
| POR | Portugal | Joana Teles | http://www.spm.pt/~opm/ | |
| PRI | Puerto Rico | Luis F. Cáceres | http://ifem.math.uprm.edu | |
| ROU | Romania | Radu Gologan | | 1959, 1960, 1969, 1978, 1999 |
| RUS | Russian Federation | Nazar Agakhanov | http://math.rusolymp.ru/ | 1992 |
| SLV | El Salvador | Carlos Mauricio Canjura Linares | | |
| SAU | Saudi Arabia | Thamer Al-Eisa | http://www.kfupm.edu.sa/mo/ | |
| SEN | Senegal | | | |
| SRB | Serbia | Djordje Dugošija | http://www.matf.bg.ac.yu/~matic/competitions/ | |
| SCG | Serbia and Montenegro | | | |
| SGP | Singapore | Chan Yew Fook | http://sms.math.nus.edu.sg/ | |
| SVK | Slovakia | Vojtech Bálint | http://matematika.webpark.sk | |
| SVN | Slovenia | Irena Majcen | http://www.dmfa.si/ | 2006 |
| SAF | South Africa | Johan Meyer | http://www.mth.uct.ac.za/~imo/ | |
| ESP | Spain | María Gaspar | http://platea.pntic.mec.es/~csanchez/olimmain.htm | 2008 |
| LKA | Sri Lanka | T. K. Wijeratne | http://www.slmatholympiad.org/ | |
| SWE | Sweden | Paul Vaderlind | http://www.math.uu.se/~dag/skolornas.html | 1991 |
| SUI | Switzerland | Lorenz Reichel | http://www.imosuisse.ch/ | |
| SYR | Syria | | | |
| TWN | Taiwan | Cheng-Der Fuh | | 1998 |
| TJK | Tajikistan | Umed Karimov | | |
| THA | Thailand | Nataphan Kitisin | | |
| TTO | Trinidad and Tobago | Indra Haraksingh | | |
| TUN | Tunisia | Seifeddine Snoussi | | |
| TUR | Turkey | Semih Koray | http://www.matematikolimpiyati.org/ | 1993 |
| NCY | Turkish Republic of Northern Cyprus | | | |
| TKM | Turkmenistan | Erol Aslan | | |
| UKR | Ukraine | Sergiy Torba | | |
| UAE | United Arab Emirates | Yousif Shahin Abdalla | | |
| UNK | United Kingdom | Geoff Smith | http://www.bmoc.maths.org/ | 1979, 2002 |
| USA | United States of America | Steven Dunbar | http://www.unl.edu/amc/ | 1981, 2001 |
| URY | Uruguay | Ariel Affonso | http://www.reu.edu.uy/jpv/proyectos/cpm/ | |
| USS | Union of the Soviet socialist republics | | | 1964, 1968, 1973 |
| UZB | Uzbekistan | Shukhrat N. Ismailov | | |
| VEN | Venezuela | Rafael Sánchez | http://www.acm.org.ve/index.php | |
| VNM | Vietnam | Nguyen An Ninh | | 2007 |
| YUG | Yugoslavia | | | 1967, 1977 |