| AFG | Afghanistan | Onder Akkusci <onderakkuscu@gmail.com> | | |
| AGO | Angola | Gabriel Boaventura <gabrielboaventura1968@gmail.com> | | |
| ALB | Albania | Adrian Naço <nacosotir@gmail.com> | https://www.ama.org.al | |
| ALG | Algeria | Abdelhafid Hadjsadok - Abdallah Rahmani <olympiades@education.gov.dz> | | |
| ARG | Argentina | Patricia Fauring <fauringpatricia@gmail.com> | http://www.oma.org.ar/ | 1997, 2012 |
| ARM | Armenia | Smbat Gogyan <gogyan@gmail.com> | http://www.olymp.am | |
| AUS | Australia | Ben Kirk <ben.kirk@amt.edu.au> | http://www.amt.edu.au/ | 1988, 2025 |
| AUT | Austria | Robert Geretschläger <robert@rgeretschlaeger.com> | https://www.oemo.at | 1976 |
| AZE | Azerbaijan | Fuad Garayev <fuad.qarayev@edu.gov.az> | | |
| BAH | Bahrain | Ebrahim Yousif <ebrahimyousifmaths@gmail.com> | | |
| BEL | Belgium | Bart Windels <bart.windels@telenet.be> | https://www.vwo.be/vwo/belgianmatholympiads | |
| BEN | Benin | Leonard Todjihounde <leonardt67@gmail.com> | | |
| BFA | Burkina Faso | Antonio Kambiré <antoniokambire@gmail.com> | https://cmathburkina.org | |
| BGD | Bangladesh | Mahbub Majumdar <where.is.mahbub@gmail.com> | http://www.matholympiad.org.bd/ | |
| BGR | Bulgaria | Stanislav Harizanov <sharizanov@gmail.com> | http://www.math.bas.bg | 1966, 1975 |
| BIH | Bosnia and Herzegovina | Muharem Avdispahić <mavdispa@pmf.unsa.ba> | | |
| BLR | Belarus | Mikhail Karpuk <m.vasilitch@gmail.com> | | |
| BOL | Bolivia | Sonia Cordero Cárdenas <soniacordero3r@gmail.com> | | |
| BRA | Brazil | Edmilson Luis Rodrigues Motta <edmilsonlrm@gmail.com> | http://www.obm.org.br/ | 2017 |
| BRU | Brunei | Syed Rozman bin Haji Syed Abd Rahim <rozmansr@hotmail.com> | | |
| BTN | Bhutan | | | |
| BWA | Botswana | Mmoloki Lekhutlile <mlekhutlile@gmail.com> | | |
| CAN | Canada | James Rickards <imo@cms.math.ca> | https://cms.math.ca/competitions/cmo/ | 1995 |
| CHI | Chile | Hernan Burgos <hernan.burgos@ufrontera.cl> | http://www.olimpiadadematematica.cl/ | |
| CHN | People's Republic of China | LI Kewen <likewen@cast.org.cn> | | 1990, 2026 |
| CIS | Commonwealth of Independent States | | | |
| CIV | Ivory Coast | Adama Coulibaly <couliba@yahoo.fr> | | |
| CMR | Cameroon | Joseph Domguia <domguia@xpand.realty> | | |
| COL | Colombia | María Falk Losada <mariadelosada@gmail.com> | http://oc.uan.edu.co | 2013 |
| CRI | Costa Rica | Comisión de las Olimpiadas Costarricenses de Matemáticas <olimpiadas.matematicas@mep.go.cr> | http://olcoma.ac.cr/ | |
| CUB | Cuba | Nelson Tomás Hernandez Reyes <nelsonh231059@gmail.com> | | 1987 |
| CYP | Cyprus | Gregory Makrides <makrides.greg@usa.net> | http://www.cms.org.cy | |
| CZE | Czech Republic | Pavel Calábek <pavel.calabek@upol.cz> | http://www.matematickaolympiada.cz/ | |
| CZS | Czechoslovakia | | | 1962, 1971, 1984 |
| DEN | Denmark | Kirsten Rosenkilde <kr@georgmohr.dk> | http://www.georgmohr.dk/ | |
| DOM | Dominican Republic | Zulaicka M. Guzmán G. <zulaicka.guzman@minerd.gob.do> | | |
| ECU | Ecuador | Jorge Chamaidan <jchamaidan@yahoo.com> | http://omec-mat.org | |
| EGY | Egypt | Eslam M. Wageed <eslam@aast.edu> | | |
| ESP | Spain | María Gaspar <mgaspar@ucm.es> | https://www.rsme.es/olimpiada-matematica-espanola | 2008 |
| EST | Estonia | Oleg Košik <oleg.koshik@ut.ee> | http://www.math.olympiaadid.ut.ee/ | |
| FIN | Finland | Anne-Maria Ernvall-Hytönen <anne-maria.ernvall-hytonen@helsinki.fi> | http://matematiikkakilpailut.fi/ | 1985 |
| FRA | France | Vincent Jugé et Johan Yebbou <vincent.juge@animath.fr> | http://www.animath.fr/ | 1983 |
| GDR | German Democratic Republic | Hans-Dietrich Gronau <gronau@uni-rostock.de> | | 1965, 1974 |
| GEO | Georgia | George Chelidze <giorgi.chelidze@kiu.edu.ge> | | |
| GER | Germany | Uwe Leck <uwe.leck@uni-flensburg.de> | https://www.mathe-wettbewerbe.de/ | 1989, 2009 |
| GHA | Ghana | Joel M. Dogoe <admin@misemaths.org> | http://www.misemaths.org | |
| GMB | Gambia | Kolapo I. Abdul <youthcarefd@yahoo.com> | | |
| GTM | Guatemala | José Carlos Bonilla <jcbonilla14@gmail.com> | | |
| HEL | Greece | Anargyros Fellouris <info@hms.gr> | http://www.hms.gr | 2004 |
| HKG | Hong Kong | Lander Lam <ccdoge@edb.gov.hk> | | 1994, 2016 |
| HND | Honduras | Comité Hondureño de Olimpiadas Matemáticas <olimpiadamatematica.honduras@gmail.com> | | |
| HRV | Croatia | Matija Bašić <mbasic@math.hr> | http://www.matematika.hr/index.php/natjecanja/ | |
| HUN | Hungary | Viktor Harangi <harangi@gmail.com> | | 1961, 1970, 1982, 2027 |
| IDN | Indonesia | Aleams Barra <aleamsbarra@gmail.com> | http://www.tomi.or.id | |
| IND | India | Prof. Prithwijit De <nc_matholy@hbcse.tifr.res.in> | http://olympiads.hbcse.tifr.res.in/subjects/mathematics | 1996 |
| IRL | Ireland | Bernd Kreussler <bernd.kreussler@mic.ul.ie> | http://www.irmo.ie | |
| IRN | Islamic Republic of Iran | Ali Partofard <alipartofard@ipm.ir> | http://www.mathysc.ir | |
| IRQ | Iraq | Cuneyt Kilic <cuneyt.kilic@fezalar.org> | | |
| ISL | Iceland | Friđrik Diego <fd@hi.is> | http://stae.is/stak/keppnin | |
| ISR | Israel | Lev Radzivilovsky <levr78@hotmail.com> | http://www.weizmann.ac.il/zemed/gillis | |
| ITA | Italy | Massimo Gobbino <massimo.gobbino@unipi.it> | http://olimpiadi.dm.unibo.it/ | |
| JAM | Jamaica | Raymond McEachin <rmceachin@hotmail.com> | | |
| JPN | Japan | 森田康夫 <info@imojp.org> | http://www.imojp.org | 2003, 2023 |
| KAZ | Kazakhstan | Gazhdembek Tursunov <daryn.intel@gmail.com> | | 2010 |
| KEN | Kenya | James Kiwanuka Katende <jkatende@uonbi.ac.ke> | http://kkmo-official.com | |
| KGZ | Kyrgyzstan | Ishmatov Makhamadkhan <matematikLL@gmail.com> | | |
| KHM | Cambodia | Meak Kamerane <kamerane.meak@rupp.edu.kh> | | |
| KOR | Republic of Korea | Prof. Suyoung Choi <kmo@kms.or.kr> | https://www.kmo.or.kr | 2000 |
| KSV | Kosovo | Armend Shabani <shoqata.matematikaneve@gmail.com> | http://www.kms-ks.org | |
| KWT | Kuwait | Adnan Abdulmuhsen <Cjakmian@kfas.org.kw> | | |
| LAO | Laos | Sackmone Sirisack <ssirisack2000@yahoo.com> | | |
| LIE | Liechtenstein | Arnaud Maret <a.maret@mathematical.olympiad.ch> | https://mathematical.olympiad.ch/en/ | |
| LKA | Sri Lanka | Chanakya J. Wijeratne <chanakya_wijeratne@yahoo.com> | http://www.slmathsolympiad.org/ | |
| LTU | Lithuania | Artūras Dubickas <arturas.dubickas@mif.vu.lt> | http://mif.vu.lt/matematikos-olimpiados/ | |
| LUX | Luxembourg | Mike Dostert <mike.dostert@education.lu> | | |
| LVA | Latvia | Maruta Avotiņa <nms@lu.lv> | http://nms.lu.lv | |
| MAC | Macau | Ieng Tak Long <itleong@um.edu.mo> | | |
| MAR | Morocco | ASENSOUYIS Hassan <hassan_asensouyis@yahoo.fr> | | |
| MAS | Malaysia | M. Suhaimi Ramly <contact@imo-malaysia.org> | https://imo-malaysia.org/ | |
| MDA | Republic of Moldova | Anatolie Topala <anatoltop@yahoo.com> | | |
| MDG | Madagascar | Fanja Rakotondrajao <frakoton@yahoo.fr> | | |
| MEX | Mexico | Rogelio Valdez Delgado <valdez@uaem.mx> | http://www.ommenlinea.org | 2005 |
| MKD | North Macedonia | Gjorgji Markoski <gorgi.markoski@gmail.com> | https://smm.org.mk/ | |
| MMR | Myanmar | Nyunt Shwe <profnshwe@gmail.com> | | |
| MNE | Montenegro | Tatjana Vujosevic <tatjana.vujosevic@iccg.edu.me> | | |
| MNG | Mongolia | Otgonbayar Uuye <otogo@num.edu.mn> | http://www.mmo.mn | |
| MOZ | Mozambique | Luis de Nascimento Paulo <nascimento@mined.gov.mz> | | |
| MRT | Mauritania | Horma Ould HAMOUD <horma04@yahoo.fr> | https://maurimath.net/Olympiades.php | |
| NCY | Turkish Republic of Northern Cyprus | | | |
| NGA | Nigeria | Promise Mebine <p.mebine@yahoo.com> | http://www.nmcabuja.org | |
| NIC | Nicaragua | Hank de Jesús Espinoza Serrano <hankchuus@yahoo.com> | http://www.asjtnic.org/ | |
| NLD | Netherlands | Quintijn Puite <olympiade@wiskundeolympiade.nl> | http://wiskundeolympiade.nl/ | 2011 |
| NOR | Norway | Dag Wessel-Berg <dag.wessel-berg@ntnu.no> | https://www.abelkonkurransen.no | 2022 |
| NPL | Nepal | Bhadra Man Tuladhar <tuladharb2@gmail.com> | | |
| NZL | New Zealand | Ross Atkins <info@mathsolympiad.org.nz> | https://www.mathsolympiad.org.nz | |
| OMN | Oman | Maya Al Azri <mayaalazri@gmail.com> | | |
| PAK | Pakistan | Sarfraz Ahmad <sarfrazahmad@cuilahore.edu.pk> | | |
| PAN | Panama | Pedro A. Marrone G. <pmarrone@opm.org.pa> | http://www.opm.org.pa/ | |
| PAR | Paraguay | Gabriela Gómez Pasquali <gabriela@omapa.org.py> | http://www.omapa.org.py | |
| PER | Peru | Comisión de Olimpiadas de la Sociedad Matemática Peruana <olimpiadas.matematicas@pucp.pe> | https://selectivos-peru.blogspot.com/ | |
| PHI | Philippines | Hazel Joy Shi <hgshi@up.edu.ph> | http://pmo.ph | |
| POL | Poland | Andrzej Grzesik <Andrzej.Grzesik@uj.edu.pl> | http://om.mimuw.edu.pl/ | 1963, 1972, 1986 |
| POR | Portugal | Joana Teles <jteles@mat.uc.pt> | http://www.spm.pt/olimpiadas | |
| PRI | Puerto Rico | Luis F. Cáceres <luis.caceres1@upr.edu> | http://om.pr | |
| PRK | Democratic People's Republic of Korea | GI CHAN KIM <drkedu@163.com> | | |
| PSE | Palestine | Samed Alhajajla <haasamed@gmail.com> | https://meshka.space | |
| ROU | Romania | Cătălin Gherghe <catalinliviu.gherghe@gmail.com> | http://rms.unibuc.ro | 1959, 1960, 1969, 1978, 1999, 2018 |
| RUS | Russian Federation | Kirill Sukhov <imo.russia@gmail.com> | http://math.rosolymp.ru/ | 1992, 2020, 2021 |
| RWA | Rwanda | Arun Shanmuganathan <shan.arun@gmail.com> | https://rwandamatholympiad.com | |
| SAF | South Africa | Liam Baker <bakerbakura@gmail.com> | http://www.samf.ac.za | 2014 |
| SAU | Saudi Arabia | Sultan Saud Albarakati <sultan.albarakati@kaust.edu.sa> | https://www.mawhiba.org | |
| SCG | Serbia and Montenegro | | | |
| SEN | Senegal | Samba Dabo <sdabo345@gmail.com> | | |
| SGP | Singapore | Teo Cheng Guan <teo_cheng_guan@moe.gov.sg> | http://sms.math.nus.edu.sg/ | |
| SLV | El Salvador | Riquelmi Salvador Cardona Fuentes <riquelmi.cardona@jovenestalento.edu.sv> | https://www.jovenestalento.edu.sv/ | |
| SRB | Serbia | Miljan Knežević <kmiljan@matf.bg.ac.rs> | https://dms.rs/ | |
| SUI | Switzerland | Arnaud Maret <a.maret@mathematical.olympiad.ch> | https://mathematical.olympiad.ch/en/ | |
| SVK | Slovakia | Stanislav Krajči <stanislav.krajci@upjs.sk> | http://skmo.sk | |
| SVN | Slovenia | Gregor Dolinar <gregor.dolinar@fe.uni-lj.si> | http://www.dmfa.si/ | 2006 |
| SWE | Sweden | Jana Madjarova <jana@chalmers.se> | http://www.mattetavling.se | 1991 |
| SYR | Syria | Hala Al Dakkak <dca.olympiad@gmail.com> | https://dca-net.org/ | |
| THA | Thailand | Thiradet Jiarasuksakun <imo_thai@ipst.ac.th> | | 2015 |
| TJK | Tajikistan | Umed Karimov <umedkarimov@gmail.com> | | |
| TKM | Turkmenistan | Arslan Hojiyev <arslanhojiyew@gmail.com> | | |
| TTO | Trinidad and Tobago | Indra Haraksingh <iharaksingh@gmail.com> | | |
| TUN | Tunisia | Taoufik Charrada <tawfik.charrada@gmail.com> | | |
| TUR | Türkiye | Azer Kerimov <kerimov@fen.bilkent.edu.tr> | https://bilimolimpiyatlari.tubitak.gov.tr/tr | 1993 |
| TWN | Taiwan | Yen-chi Roger Lin <yclinpa@gmail.com> | https://tpmso.org/tmo/ | 1998 |
| TZA | Tanzania | Ertugrul Tarhan <ertugrultarhan72@gmail.com> | | |
| UAE | United Arab Emirates | Abdallah El Marhoune <Abdallah.Elmarhoune@moe.gov.ae> | http://competitions.ae/masterminds/ | |
| UGA | Uganda | Joseph Ssebuliba <ssebulibaa@gmail.com> | https://ums.ug/ | |
| UKR | Ukraine | Bogdan Rublov <rublyovbv@gmail.com> | http://matholymp.com.ua/ | |
| UNK | United Kingdom | Geoff Smith <geoffsmith1729@gmail.com> | http://www.bmoc.maths.org/ | 1979, 2002, 2019, 2024 |
| URY | Uruguay | Nelson Chocca <nchocca@gmail.com> | http://com-partidauruguay.weebly.com/ | |
| USA | United States of America | Nicole Goberdhan <amchq@maa.org> | http://amc.maa.org | 1981, 2001 |
| USS | Union of Soviet Socialist Republics | | | 1964, 1968, 1973 |
| UZB | Uzbekistan | Utkir Boltaev <uboltayev@gmail.com> | http://olympiad.uzedu.uz | |
| VEN | Venezuela | Rafael Sánchez <lamonedar@gmail.com> | https://www.acmven.org | |
| VNM | Vietnam | Le Anh Vinh <leanhvinh@gmail.com> | | 2007 |
| YEM | Yemen | Munaf Abood <munafabood@hotmail.com> | | |
| YUG | Yugoslavia | | | 1967, 1977 |
| ZWE | Zimbabwe | A Stewart <stewarta@maths.uz.ac.zw> | | |
