The Australian Army Training Team Vietnam (AATTV) was a specialist unit of military advisors of the Australian Army that operated during the Vietnam War. Raised in 1962, the unit was formed solely for service as part of Australia's contribution to the war, providing training and assistance to South Vietnamese forces. Initially numbering only approximately 30 men, the size of the unit grew several times over the following years as the Australian commitment to South Vietnam gradually grew, with the unit's strength peaking at 227 in November 1970. Members of the team worked individually or in small groups, operating throughout the country from the far south to the Demilitarized Zone (DMZ) in the north. Later they were concentrated in Phước Tuy Province as Australian forces prepared to withdraw from Vietnam. It is believed to be the most decorated Australian unit to serve in Vietnam; its members received over 100 decorations, including four Victoria Crosses, during its existence. The unit was withdrawn from South Vietnam on 18 December 1972 and was disbanded in Australia on 16 February 1973. A total of 1,009 men served with the unit over a period of ten years, consisting of 998 Australians and 11 New Zealanders.

A Military Assistance Advisory Group (MAAG) is a designation for a group of United States military advisors sent to other countries to assist in the training of conventional armed forces and facilitate military aid. Although numerous MAAGs operated around the world throughout the 1940s–1970s, including in Yugoslavia after 1951, the most famous MAAGs were those active in Southeast Asia before and during the Vietnam War.