List of mathematics competitions

International mathematics competitions

IMO (International Mathematical Olympiad) -- worldwide
IMC (International Mathematics Competition for University Students) [1] (http://www.imc-math.org)
PMWC (Primary Mathematics World Contest) -- worldwide

Regional mathematics competitions

SEAMO (SEAMEO Mathematics Olympiad) -- South-East Asia
APMO (Asian-Pacific Mathematics Olympiad) -- Pacific rim
OIM (Olimpíadas Iberoamericanas de Matemática) -- Spain, Portugal and Latin America
Olimpiada Matematica de Centroamérica y del Caribe -- Central America and the Caribbean
Olimpiada Matematica de Paises del Cono Sur -- 8 countries from South America
Balkan Mathematical Olympiad -- Balkan area
William Lowell Putnam Mathematical Competition -- USA and Canada (http://www.maa.org/awards/putnam.html )
Baltic Way -- Baltic area.

National mathematics competitions

Argentina

OMA (Olimpíada Matemática Argentina)

Australia

AMC (Australian Mathematics Competition)

Austria

ÖMO (Österreichische Mathematik-Olympiade) (http://www.oemo.at )

Belgium

OMB (Olympiade Mathématique Belge)
VWO (Vlaamse Wiskunde Olympiade)

Brazil

OBM (Olimpíada Brasileira de Matemática)
Olimpíada Paulista

Canada

National competitions hosted by The Centre for Education in Mathematics and Computing (http://www.cemc.uwaterloo.ca/):

Full Solutions:

Euclid (12th grade students)
Hypatia (11th grade students)
Galois (10th grade students)
Fryer (9th grade students)

Multiple Choice:

Fermat (11th grade students)
Cayley (10th grade students)
Pascal (9th grade students)
Gauss (7th and 8th grade students)

Other competitions hosted by The Canadian Mathematical Society (http://www.cms.math.ca/):

COMC (Canadian Open Mathematics Challenge)
CMO (Canadian Mathematics Olympiad)

MATHChallengers (http://www.apeg.bc.ca/mathchallengers/) (formerly MathCounts BC) is called MATHChallegers since 2005. It is hosted by APEGBC (http://www.apeg.bc.ca/index.html).

Cyprus

Κυπριακή Μαθηματική Ολυμπιάδα (Cyprus Mathematical Olympiad) - Mathematics competitions for students of all ages.
Επαρχιακοί Διαγωνισμοί Β΄ και Γ΄ τάξεων Λυκείων (Provincial Competitions for 2nd and 3rd grades of Lycea)
Παγκύπριος Διαγωνισμος Λυκείου "Ζήνων" ("Zeno" Competition of Lyceum)
Παγκύπριος Διαγωνισμος Α΄ Λυκείου "Πετράκης Γιάλλουρος" ("Petrakis Yallouros" Competition for 1st grade of Lyceum) - For students under 15.5 years old
Παγκύπριος Διαγωνισμος Γ΄ Λυκείου "Ευαγόρας Παλληκαρίδης" ("Evagoras Pallikarides" Competition for 3rd grade of high school) - For students under 15.5 years old

Denmark

Georg Mohr (Contest for Danish high school students, see http://www.imf.au.dk/georg-mohr/hvemvargm.html for more details [note: in Danish])

Germany

DeMO (Deutsche Mathematik-Olympiade, http://www.mathematik-olympiaden.de)

Hong Kong, China

HKMO (香港數學競賽, Hong Kong Mathematics Olympiad)
HKMHASC (The Hong Kong Mathematical High Achievers Selection

Contest, for form 1 to 3 students, Homepage in Chinese(flash): http://tyt.hkcampus.net/hkmhasc/)

Hungary

Kalmár László Országos Matematika Verseny (3rd to 8th grade students)
Kömal (a year-long contest, each month you have to submit solutions to some problems, 9th-12th grade, Homepage in English: http://www.komal.hu/info/bemutatkozas.e.shtml )
ADMV (Arany Dániel Matematika Verseny, 9th and 10th grade students)
OKTV (Országos Középiskolai Tanulmányi Verseny, 11th and 12th grade)
Kürschák József (first year university students or below)

Netherlands

NWO (Nederlandse Wiskunde Olympiade)

Norway

Niels Henrik Abels matematikk-konkurranse (Norwegian Mathematical Olympiad, website available both in Norwegian and English at http://www.math.uio.no/abelkonkurransen/ )

Philippines

Philippine Mathematics Olympiad

Portugal

Portuguese Mathematics Olympiad - Olimpíadas Portuguesas da Matemática (in Portuguese) (http://www.mat.uc.pt/~opm/)
Olimpíada Paulistas (with Brazil)

Slovakia

MO Matematická olymipáda http://matematika.webpark.sk
STROM Korešpondenčné matematické semináre http://www.strom.sk
KMS Korešpondenčný matematický seminár http://kms.sk/

Sweden

Skolornas matematiktävling (see http://www.math.uu.se/~dag/skolornas.html or http://www.math.chalmers.se/~sam/problemet/bok.html for older problems)
Högstadiets matematiktävling (http://www.matematiktavling.org/hmt/, open for students in grades 7 through 9)

United Kingdom

Junior Maths Challenge
Intermediate Maths Challenge
Senior Maths Challenge (formerly National Maths Contest)
British Mathematical Olympiad (http://www.bmoc.maths.org/)

United States

National college competitions

Regional competitions

See List of United States regional mathematics competitions.