The South African Irish Regiment is an infantry regiment of the South African Army. As a reserve unit, it has a status roughly equivalent to that of a British Territorial Army or United States Army National Guard unit.

The South African Irish was formed at the outbreak of World War I in August 1914 when three officers (Major George Twomey, Captain J. Jeoffreys and a Captain MacDonald) met at the Irish Club in Johannesburg in order to raise an Irish regiment from among the citizens of Johannesburg and its surrounding areas.

At the outbreak of World War II in 1939 the 1st South African Irish Regiment was reformed through the efforts of Major Twomey, Captains Jeoffreys and Cullinan (the latter was the son of Sir Thomas Cullinan, of diamond fame).

At the end of World War II it was requested that the Regiment be reformed as an infantry unit. However, as there was no intention at that time to establish additional Active Citizen Force infantry battalions, this request was refused. However, as a form of compensation, authority was granted for the formation of an artillery unit with the designation of 22 Field Regiment (South African Irish), South African Artillery. This unit was formed in June 1946 and it operated until 31 December 1959 as an artillery regiment. However, on 1 January 1960 the regiment was converted back to an infantry unit and regained its old nomenclature, the South African Irish Regiment.