| ALB | Albania | Fatmir Hoxha | | |
| ALG | Algeria | Ali Atia | | |
| ARG | Argentina | Patricia Fauring | http://www.oma.org.ar/ | 1997, 2012 |
| ARM | Armenia | Nairi Sedrakyan | | |
| 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 | http://www.vwo.be/vwo/ | |
| BEN | Benin | Kpamegan Bernardin | | |
| BOL | Bolivia | Sonia Cordero Cárdenas | | |
| BIH | Bosnia and Herzegovina | Muharem Avdispahić | | |
| BRA | Brazil | Nelly Carvajal | http://www.obm.org.br/ | |
| BRU | Brunei | Syed Rozman bin Haji Syed Abd Rahim | | |
| BGR | Bulgaria | Nikolai Nikolov | http://www.math.bas.bg | 1966, 1975 |
| KHM | Cambodia | Lin Sok | | |
| CAN | Canada | Johan Rudnick | http://www.cms.math.ca/Olympiads/ | 1995 |
| CHI | Chile | Hernan Burgos | http://www.olimpiadadematematica.cl/ | |
| CHN | People's Republic of China | QIAN Cheng | | 1990 |
| COL | Colombia | María Falk de Losada | http://olimpia.uan.edu.co | |
| CIS | Commonwealth of Independent States | | | |
| CRI | Costa Rica | Mario Marín Sánchez | | |
| HRV | Croatia | Željko Hanjš | http://www.matematika.hr/hrvatska | |
| CUB | Cuba | Carlos Sifredo Barrios | | 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 | Jens-Søren K. Andersen | http://www.georgmohr.dk/ | |
| ECU | Ecuador | Vicente Torres Álvarez | | |
| EST | Estonia | Härmel Nestra | http://www.math.olympiaadid.ut.ee/ | |
| FIN | Finland | Matti Lehtinen | http://solmu.math.helsinki.fi/olympia/ | 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 | Comité Hondureño de Olimpiadas Matemáticas | | |
| 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 | H.C. Pradhan | http://cce.iisc.ernet.in/math.html | 1996 |
| IDN | Indonesia | Hery Susanto | | |
| IRN | Islamic Republic of Iran | Arash Rastegar | http://www.ysc.ac.ir | |
| IRL | Ireland | Tom Laffey | http://www.ul.ie/~maths/imo.htm | |
| ISR | Israel | Shay Gueron | http://math.haifa.ac.il/~israelmo/ | |
| ITA | Italy | Roberto Dvornicich | http://olimpiadi.dm.unipi.it/ | |
| CIV | Ivory Coast | Isaac Tape | http://www.fondationamex.org | |
| 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 |
| KSV | Kosovo | Ramadan Limani | | |
| KWT | Kuwait | Jasem Al-Besharah | | |
| KGZ | Kyrgyzstan | Boljiev Buras Asanbekovich | | |
| LVA | Latvia | Agnis Andžāns | http://nms.lu.lv | |
| LIE | Liechtenstein | Julian Kellerhals | | |
| LTU | Lithuania | Romualdas Kasuba | http://www.olimpiados.lt/ | |
| LUX | Luxembourg | Charles Leytem | | |
| MAC | Macau | Ieng Tak Long | | |
| MKD | The former Yugoslav Republic of Macedonia | Vesna Manova - Erakovik | | |
| MAS | Malaysia | M. Suhaimi Ramly | http://www.persama.org.my/ | |
| MRT | Mauritania | Ould Farajou Isselmou | http://www.resafad.mr/OlympiadesRIM.html | |
| MEX | Mexico | Radmila Bulajich Manfrino | http://www.eduunam.com/ | 2005 |
| MDA | Republic of Moldova | Ceapa Valentina | | |
| MNG | Mongolia | Dashdorj Ts | | |
| MNE | Montenegro | Verica Ivanovic | | |
| MAR | Morocco | Moussaoui My Ahmed | | |
| MOZ | Mozambique | Luis de Nascimento Paulo | | |
| NLD | Netherlands | Quintijn Puite | http://wiskundeolympiade.nl/ | 2011 |
| NZL | New Zealand | Christopher Tuffley | http://www.mathsolympiad.org.nz | |
| NIC | Nicaragua | | | |
| NGA | Nigeria | Steve Oluwaniyi | http://www.nmcabuja.org | |
| NOR | Norway | Øyvind Bakke | http://abelkonkurransen.no/ | |
| PAK | Pakistan | Alla Ditta Choudary | | |
| PAN | Panama | Pedro A. Marrone G. | http://www.opm.org.pa/ | |
| PAR | Paraguay | Gabriela Gómez Pasquali | http://www.omapa.org.py | |
| PER | Peru | Emilio Gonzaga Ramírez | http://www.somape.org.pe | |
| PHI | Philippines | Ian June L. Garces | http://mathsci.math.admu.edu.ph/pmo | |
| POL | Poland | Michał Pilipczuk | http://www.om.edu.pl/ | 1963, 1972, 1986 |
| POR | Portugal | Joana Teles | http://www.spm.pt/olimpiadas | |
| PRI | Puerto Rico | Luis F. Cáceres | http://ifem.math.uprm.edu | |
| ROU | Romania | Radu Gologan | http://rms.unibuc.ro | 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 | Abdulaziz S. Al-Harthi | http://www.smo.org.sa | |
| SEN | Senegal | Samba Dabo | | |
| SRB | Serbia | Đorđe Krtinić | http://srb.imomath.com/ | |
| SCG | Serbia and Montenegro | | | |
| SGP | Singapore | Oi Mei Teo | http://sms.math.nus.edu.sg/ | |
| SVK | Slovakia | Peter Novotný | http://skmo.sk | |
| SVN | Slovenia | Gregor Dolinar | 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 | C. J. Wijeratne | http://www.slmathsolympiad.org/ | |
| SWE | Sweden | Paul Vaderlind | http://www.math.uu.se/~dag/skolornas.html | 1991 |
| SUI | Switzerland | Anna Devic | http://www.imosuisse.ch/ | |
| SYR | Syria | | | |
| TWN | Taiwan | Cheng-Der Fuh | | 1998 |
| TJK | Tajikistan | Umed Karimov | | |
| THA | Thailand | Wicharn Lewkeeratiyutkul | | |
| 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 | Bogdan Rublyov | | |
| UAE | United Arab Emirates | Aaesha Jassem Alshamsi | | |
| 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 | Nelson Chocca | http://www.reu.edu.uy/jpv/proyectos/cpm/ | |
| USS | Union of Soviet Socialist Republics | | | 1964, 1968, 1973 |
| UZB | Uzbekistan | Shuhrat N. Ismailov | | |
| VEN | Venezuela | Rafael Sánchez | http://www.acm.org.ve/index.php | |
| VNM | Vietnam | Nguyen An Ninh | | 2007 |
| YUG | Yugoslavia | | | 1967, 1977 |
| ZWE | Zimbabwe | Erica Keogh | | |