| ZWE | Zimbabwe | A Stewart <stewarta@maths.uz.ac.zw> | | |
| YUG | Yugoslavia | | | 1967, 1977 |
| YEM | Yemen | Munaf Abood <munafabood@hotmail.com> | | |
| VNM | Vietnam | Le Anh Vinh <leanhvinh@gmail.com> | | 2007 |
| VEN | Venezuela | Rafael Sánchez <lamonedar@gmail.com> | https://www.acmven.org | |
| UZB | Uzbekistan | Rustam Turdibaev <dr.turdibaev@gmail.com> | http://olympiad.uzedu.uz | |
| USS | Union of Soviet Socialist Republics | | | 1964, 1968, 1973 |
| URY | Uruguay | Nelson Chocca <nchocca@gmail.com> | http://com-partidauruguay.weebly.com/ | |
| USA | United States of America | Jennifer Barton <amchq@maa.org> | http://amc.maa.org | 1981, 2001 |
| UNK | United Kingdom | Geoff Smith <G.C.Smith@bath.ac.uk> | http://www.bmoc.maths.org/ | 1979, 2002, 2019 |
| UAE | United Arab Emirates | Abdallah El Marhoune <Abdallah.Elmarhoune@moe.gov.ae> | http://www.olympiads.org | |
| UKR | Ukraine | Bogdan Rublov <rublyovbv@gmail.com> | http://matholymp.com.ua/ | |
| UGA | Uganda | Okello Jasper <jhokello@gmail.com> | | |
| TKM | Turkmenistan | Arslan Hojiyev <arslanhojiyew@gmail.com> | | |
| NCY | Turkish Republic of Northern Cyprus | | | |
| TUR | Turkey | Azer Kerimov <kerimov@fen.bilkent.edu.tr> | http://www.matematikolimpiyati.org/ | 1993 |
| TUN | Tunisia | Taoufik Charrada <tawfik.charrada@gmail.com> | | |
| TTO | Trinidad and Tobago | Indra Haraksingh <iharaksingh@gmail.com> | | |
| THA | Thailand | Sukit Limpijumnong <imo_thai@ipst.ac.th> | | 2015 |
| TZA | Tanzania | Ertugrul Tarhan <ertugrultarhan@yahoo.com> | | |
| TJK | Tajikistan | Umed Karimov <umedkarimov@gmail.com> | | |
| TWN | Taiwan | John Meng-Kai Hong <jhong@math.ncu.edu.tw> | http://imotwn.math.ncu.edu.tw/ | 1998 |
| SYR | Syria | Hala Al Dakkak <dca.olympiad@gmail.com> | http://www.sso.sy | |
| SUI | Switzerland | Arnaud Maret (imosuisse) <vorstand@imosuisse.ch> | https://mathematical.olympiad.ch/en/ | |
| SWE | Sweden | Jana Madjarova <jana@chalmers.se> | http://www.mattetavling.se | 1991 |
| LKA | Sri Lanka | Chanakya J. Wijeratne <chanakya_wijeratne@yahoo.com> | http://www.slmathsolympiad.org/ | |
| ESP | Spain | María Gaspar <mgaspar@ucm.es> | http://platea.pntic.mec.es/~csanchez/olimmain.htm | 2008 |
| SAF | South Africa | Johan Meyer <meyerjh@ufs.ac.za> | http://www.samf.ac.za | 2014 |
| SVN | Slovenia | Gregor Dolinar <gregor.dolinar@fe.uni-lj.si> | http://www.dmfa.si/ | 2006 |
| SVK | Slovakia | Peter Novotný <novotny.peto@gmail.com> | http://skmo.sk | |
| SGP | Singapore | Ai Xinghuan <ai_xinghuan@moe.gov.sg> | http://sms.math.nus.edu.sg/ | |
| SCG | Serbia and Montenegro | | | |
| SRB | Serbia | Dušan Đukić <dusan.djukic@utoronto.ca> | http://srb.imomath.com/ | |
| SEN | Senegal | Samba Dabo <sdabo345@gmail.com> | | |
| SAU | Saudi Arabia | Fawzi A. Al-Thukair <thukair@ksu.edu.sa> | http://www.smo.org.sa | |
| SLV | El Salvador | Gabriel Alexander Chicas Reyes <gabriel.chicas@ues.edu.sv> | https://www.jovenestalento.edu.sv/ | |
| RUS | Russian Federation | Kirill Sukhov <imo.russia@gmail.com> | http://math.rosolymp.ru/ | 1992, 2020, 2021 |
| ROU | Romania | Catalin Gherghe <catalinliviu.gherghe@gmail.com> | http://rms.unibuc.ro | 1959, 1960, 1969, 1978, 1999, 2018 |
| PRI | Puerto Rico | Luis F. Cáceres <luis.caceres1@upr.edu> | http://om.pr | |
| POR | Portugal | Joana Teles <jteles@mat.uc.pt> | http://www.spm.pt/olimpiadas | |
| POL | Poland | Andrzej Grzesik <Andrzej.Grzesik@uj.edu.pl> | http://om.mimuw.edu.pl/ | 1963, 1972, 1986 |
| PHI | Philippines | Christian Paul O. Chan Shio <cchanshio@ateneo.edu> | http://pmo.ph | |
| PER | Peru | Comisión de Olimpiadas de la Sociedad Matemática Peruana <olimpiadas.matematicas@pucp.pe> | https://selectivos-peru.blogspot.com/ | |
| PAR | Paraguay | Gabriela Gómez Pasquali <gabriela@omapa.org.py> | http://www.omapa.org.py | |
| PAN | Panama | Pedro A. Marrone G. <pmarrone@opm.org.pa> | http://www.opm.org.pa/ | |
| PAK | Pakistan | Sarfraz Ahmad <sarfrazahmad@cuilahore.edu.pk> | | |
| OMN | Oman | Maya Al Azri <mayaalazri@gmail.com> | | |
| NOR | Norway | Harald Hanche-Olsen <hanche@math.ntnu.no> | http://abelkonkurransen.no/ | 2022 |
| MKD | North Macedonia | Gjorgji Markoski <gorgi.markoski@gmail.com> | https://smm.org.mk/ | |
| NGA | Nigeria | Stephen E.Onah <ajusonah2001@yahoo.com> | http://www.nmcabuja.org | |
| NIC | Nicaragua | Hank de Jesús Espinoza Serrano <hankchuus@yahoo.com> | http://www.asjtnic.org/ | |
| NZL | New Zealand | Ross Atkins <info.nzmoc@gmail.com> | https://www.mathsolympiad.org.nz | |
| NLD | Netherlands | Quintijn Puite <olympiade@wiskundeolympiade.nl> | http://wiskundeolympiade.nl/ | 2011 |
| NPL | Nepal | Bhadra Man Tuladhar <tuladharb2@gmail.com> | | |
| MMR | Myanmar | Nyunt Swe <prof.nyuntswe@gmail.com> | | |
| MOZ | Mozambique | Luis de Nascimento Paulo <nascimento@mined.gov.mz> | | |
| MAR | Morocco | Berraho Mohamed <med.berraho@gmail.com> | | |
| MNE | Montenegro | Tatjana Vujosevic <tatjana.vujosevic@iccg.edu.me> | | |
| MNG | Mongolia | Batbayasgalan Balkhuu <batbayasgalan@num.edu.mn> | http://www.mmo.mn | |
| MDA | Republic of Moldova | Anatolie Topala <anatoltop@yahoo.com> | | |
| MEX | Mexico | Rogelio Valdez Delgado <valdez@uaem.mx> | http://www.ommenlinea.org | 2005 |
| MRT | Mauritania | Ould Farajou Isselmou <farajou@yahoo.fr> | http://www.resafad.mr/OlympiadesRIM.html | |
| MAS | Malaysia | M. Suhaimi Ramly <contact@imo-malaysia.org> | https://imo-malaysia.org/ | |
| MDG | Madagascar | Fanja Rakotondrajao <frakoton@yahoo.fr> | | |
| MAC | Macau | Ieng Tak Long <itleong@um.edu.mo> | | |
| LUX | Luxembourg | Mike Dostert <mike.dostert@education.lu> | http://math.uni.lu/matholymp | |
| LTU | Lithuania | Artūras Dubickas <arturas.dubickas@mif.vu.lt> | http://mif.vu.lt/matematikos-olimpiados/ | |
| LIE | Liechtenstein | Robert Meier <robert@imosuisse.ch> | | |
| LVA | Latvia | Maruta Avotiņa <nms@lu.lv> | http://nms.lu.lv | |
| LAO | Laos | Sackmone Sirisack <ssirisack2000@yahoo.com> | | |
| KGZ | Kyrgyzstan | Ishmatov Makhamadkhan <matematikLL@gmail.com> | | |
| KWT | Kuwait | Adnan Abdulmuhsen <Cjakmian@kfas.org.kw> | | |
| KSV | Kosovo | Armend Shabani <shoqata.matematikaneve@gmail.com> | http://www.kms-ks.org | |
| KOR | Republic of Korea | Yongjin Song <yjsong@inha.ac.kr> | http://www.kmo.or.kr | 2000 |
| PRK | Democratic People's Republic of Korea | GI CHAN KIM <drkedu@163.com> | | |
| KEN | Kenya | James Kiwanuka Katende <jkatende@uonbi.ac.ke> | http://kkmo-official.com | |
| KAZ | Kazakhstan | Akzhol Boranbay <daryn.intel@gmail.com> | | 2010 |
| JPN | Japan | Yasuo Morita <info@imojp.org> | http://www.imojp.org | 2003, 2023 |
| JAM | Jamaica | Raymond McEachin <rmceachin@hotmail.com> | | |
| CIV | Ivory Coast | Adama Coulibaly <couliba@yahoo.fr> | | |
| ITA | Italy | Massimo Gobbino <massimo.gobbino@unipi.it> | http://olimpiadi.dm.unibo.it/ | |
| ISR | Israel | Lev Radzivilovsky <levr78@hotmail.com> | http://www.weizmann.ac.il/zemed/gillis | |
| IRL | Ireland | Bernd Kreussler <bernd.kreussler@mic.ul.ie> | http://www.irmo.ie | |
| IRN | Islamic Republic of Iran | Erfan Salavati <erfan.salavati@aut.ac.ir> | http://www.mathysc.ir | |
| IRQ | Iraq | Cuneyt Kilic <cuneyt.kilic@fezalar.org> | | |
| IDN | Indonesia | Aleams Barra <aleamsbarra@gmail.com> | http://www.tomi.or.id | |
| IND | India | K. Subramaniam <director@hbcse.tifr.res.in> | http://olympiads.hbcse.tifr.res.in/subjects/mathematics | 1996 |
| ISL | Iceland | Friđrik Diego <fd@hi.is> | http://stae.is/stak/keppnin | |
| HUN | Hungary | Péter Frenkel <frenkelp265@gmail.com> | | 1961, 1970, 1982 |
| HKG | Hong Kong | Candice Ng <ccdoge@edb.gov.hk> | | 1994, 2016 |
| HND | Honduras | Comité Hondureño de Olimpiadas Matemáticas <olimpiadamatematica.honduras@gmail.com> | | |
| GTM | Guatemala | José Carlos Bonilla <jcbonilla14@gmail.com> | | |
| HEL | Greece | Anargyros Fellouris <info@hms.gr> | http://www.hms.gr | 2004 |
| GHA | Ghana | Joel M. Dogoe <mise.foundation@gmail.com> | http://www.misemaths.org | |
| GER | Germany | Jürgen Prestin <prestin@math.uni-luebeck.de> | https://www.mathe-wettbewerbe.de/ | 1989, 2009 |
| GDR | German Democratic Republic | Hans-Dietrich Gronau <gronau@uni-rostock.de> | | 1965, 1974 |
| GEO | Georgia | George Chelidze <g_chelidze@hotmail.com> | | |
| GMB | Gambia | Kolapo I. Abdul <youthcarefd@yahoo.com> | | |
| FRA | France | Vincent Jugé et Johan Yebbou <vincent.juge@u-pem.fr> | http://www.animath.fr/ | 1983 |
| FIN | Finland | Anne-Maria Ernvall-Hytönen <aernvall@abo.fi> | http://matematiikkakilpailut.fi/ | 1985 |
| EST | Estonia | Oleg Košik <oleg.koshik@ut.ee> | http://www.math.olympiaadid.ut.ee/ | |
| EGY | Egypt | Yasser Tawfik <yasser@ideasgym.com> | | |
| ECU | Ecuador | Vicente Torres Álvarez <vitorres906@gmail.com> | http://omec-mat.org | |
| DOM | Dominican Republic | Ligia Henriquez <ligia.henriquez@minerd.gob.do> | | |
| DEN | Denmark | Kirsten Rosenkilde <kr@georgmohr.dk> | http://www.georgmohr.dk/ | |
| CZS | Czechoslovakia | | | 1962, 1971, 1984 |
| CZE | Czech Republic | Svrcek Jaroslav <jaroslav.svrcek@upol.cz> | http://www.matematickaolympiada.cz/ | |
| CYP | Cyprus | Gregory Makrides <makrides.greg@usa.net> | http://www.cms.org.cy | |
| CUB | Cuba | Enech García Martínez <enech@cubaeduca.cu> | | 1987 |
| HRV | Croatia | Mea Bombardelli <bombarde@math.hr> | http://www.matematika.hr/index.php/natjecanja/ | |
| CRI | Costa Rica | Comisión de las Olimpiadas Costarricenses de Matemáticas <olimpiadas.matematicas@mep.go.cr> | http://olcoma.ucr.ac.cr/ | |
| CIS | Commonwealth of Independent States | | | |
| COL | Colombia | María Falk de Losada <mariadelosada@gmail.com> | http://oc.uan.edu.co | 2013 |
| CHN | People's Republic of China | Qian Cheng <qiancheng@cast.org.cn> | | 1990 |
| CHI | Chile | Hernan Burgos <hernan.burgos@ufrontera.cl> | http://www.olimpiadadematematica.cl/ | |
| CAN | Canada | Sarah Watson <imo@cms.math.ca> | http://www.cms.math.ca/Olympiads/ | 1995 |
| KHM | Cambodia | Meak Kamerane <kamerane.meak@rupp.edu.kh> | | |
| BFA | Burkina Faso | Victor Barry <victoraso2005@yahoo.fr> | | |
| BGR | Bulgaria | Peter Boyvalenkov <peter@math.bas.bg> | http://www.math.bas.bg | 1966, 1975 |
| BRU | Brunei | Syed Rozman bin Haji Syed Abd Rahim <rozmansr@hotmail.com> | | |
| BRA | Brazil | Edmilson Luis Rodrigues Motta <edmilsonlrm@gmail.com> | http://www.obm.org.br/ | 2017 |
| BWA | Botswana | Mmoloki Lekhutlile <mlekhutlile@yahoo.com> | | |
| BIH | Bosnia and Herzegovina | Muharem Avdispahić <mavdispa@pmf.unsa.ba> | | |
| BOL | Bolivia | Sonia Cordero Cárdenas <soniacordero3r@gmail.com> | | |
| BEN | Benin | Leonard Todjihounde <leonardt67@gmail.com> | | |
| BEL | Belgium | Bart Windels <bart.windels@telenet.be> | https://www.vwo.be/vwo/belgianmatholympiads | |
| BLR | Belarus | Alena Senchanka <esenchenko@minedu.unibel.by> | | |
| BGD | Bangladesh | Mahbub Majumdar <where.is.mahbub@gmail.com> | http://www.matholympiad.org.bd/ | |
| BAH | Bahrain | Ebrahim Yousif <ebrahimyousifmaths@gmail.com> | | |
| AZE | Azerbaijan | Fuad Garayev <f.qarayev@arti.edu.az> | | |
| AUT | Austria | Robert Geretschläger <robert@rgeretschlaeger.com> | https://www.oemo.at | 1976 |
| AUS | Australia | Nathan Ford <nathan.ford@amt.edu.au> | http://www.amt.edu.au/ | 1988, 2025 |
| ARM | Armenia | Smbat Gogyan <gogyan@gmail.com> | http://www.olymp.am | |
| ARG | Argentina | Patricia Fauring <patri@cbc.uba.ar> | http://www.oma.org.ar/ | 1997, 2012 |
| AGO | Angola | Gabriel Boaventura <gabrielboaventura1968@gmail.com> | | |
| ALG | Algeria | Abdellah Rahmani, Abdelhafid Hadjsadok <olympiades@education.gov.dz> | | |
| ALB | Albania | Adrian Naço <nacosotir@gmail.com> | https://www.ama.org.al | |
| AFG | Afghanistan | Onder Akkusci <onderakkuscu@gmail.com> | | |
