The Irish Chess Union (ICU; Irish: Aontas Fichille na hÉireann^[1][2]), is the governing body for chess in Ireland since its formation in 1912. ICU is a member of FIDE since 1933^[3] and the European Chess Union. The ICU promotes chess in Ireland and maintains the chess rating for players registered with the ICU, which are published monthly. It runs competitions such as the Irish Chess Championship and selects teams to participate in international competitions for Ireland.

In 2005, in a dispute over fees, the Ulster Chess Union (UCU), which administers and develops chess in Northern Ireland, decided to end its affiliation with the Irish Chess Union, although the UCU accepted the ICU's continued organisation of the All-Ireland Championships.^[4] The UCU's application to affiliate to FIDE was rebuffed.^[5] In September 2018 the UCU re-affiliated to the ICU.^[6]

Chess in Ireland has been concentrated around the major cities of Dublin, Belfast and Cork; there are also a number of clubs throughout the country such as those in Ballinasloe, Derry, Drogheda, Drumlish, Ennis, Enniscorthy, Galway, Kilkenny, Portadown Lisburn and Wicklow. Leagues are held in the provinces, with the winning teams (and runners-up) playing off in the National Club Championships (although in recent years the Ulster leagues have not participated). The winning team and runners-up are entered into the European Club Championships.

Chess has been played in Ireland since medieval times. Chess was played and groups met with different degrees of formality in Dublin in the eighteenth and nineteenth century, such as an early incarnation of a Dublin Chess Club from 1813 to 1819 and The Dublin Philidorian Chess Society, which was formed at the Harp Coffee House in Dublin in 1819. Before the establishment of the ICU in 1912, chess competitions in Ireland were run under organisations named The Irish Chess Association (formed in 1885), the Hibernia Chess Association, or various chess clubs. Thomas Long^[7] who organised the 1865 Dublin Masters was the first president/chairman of The Irish Chess Association, he also helped found the Dublin Chess Club in 1867, the oldest chess club in Ireland. The Armstrong Cup is the oldest Irish team league competition and has been played every year since 1888, perhaps giving it a claim on the longest running chess competition in the world.

The ICU had published magazines in the past such as the Irish Chess Journal for members of the association. In 2007, to reduce costs, this has been curtailed to a biannual online magazine. Since 2009 no journal has been produced. Junior Chess Corner was a magazine/ezine produced in 2007 by the ICU aimed at juniors and beginners.

There have been a number of incarnations of the official magazine from the ICU, such as Ficheall/Irish Chess Magazine in the 1950s and Chess in Ireland,^[8] in the 1960s.

Competitions are held throughout the year mostly run by individual clubs or by provincial Unions such as the City of Dublin, Cork Congress (Mulcahy Cup), Bunratty, Limerick Open, Gonzaga Classic, Galway Congress, Drogheda, Malahide, Bray, Kilkenny Congress, Ulster and Leinster Championships.

A number of significant tournaments have been held in the past

• 1865 Dublin Masters
• 1892 North of Ireland Congress, Belfast
• 1924 Tailteann Games, Dublin
• 1928 Tailteann Games, Dublin
• 1932 Tailteann Games, Dublin
• 1951 Clontarf International, Dublin
• 1954 An Tóstal, Dublin
• 1955 An Tóstal, Cork
• 1956 An Tóstal, Dublin^[9]
• 1957 An Tóstal, Dublin
• 1957 Dublin Zonal
• 1962 O'Hanlon Memorial (ICU Golden Jubilee), Dublin
• 1988 CIMA Dublin Millennium Chess Congress
• 1991 Telecom Éireann International, Dublin
• 1993 Dublin FIDE Zonal
• 2005 European Union Chess Championship, Cork

Underage/Schools Chess Provincial and All Ireland competitions are held annually. The Leinster Schools Chess Association was established in 1942 running leagues through the school term, and holding the provincial championships over the Christmas holidays.^[15] The All-Ireland Schools Competition is usually held during the Easter School Holidays. Chess also features as part of the Community Games.^[16]

The Braille Chess Association of Ireland was established in 1985 to promote Chess among the blind and partially sighted. The BCAI is affiliated to the International Braille Chess Association, the Irish Chess Union and National Council for the Blind of Ireland/Irish BlindSports.^[21] They hold the National Championships and organise teams and players for international Competitions.^[22]

Affiliated to the Irish Chess Union is the Irish Correspondence Chess Association (ICCA) which is the 32-county governing body organising correspondence chess activities for Irish players living at home or abroad. A non-profit organisation, they run the national championship, Irish teams and other activities. The ICCA is affiliated to the International Correspondence Chess Federation (ICCF).^[23]