The Provisional Revolutionary Government of the Republic of South Vietnam (Chính Phủ Cách Mạng Lâm Thời Cộng Ḥa Miền Nam Việt Nam) was a Communist government formed by the National Liberation Front (NLF) in 1969 in opposition to the anti-Communist U.S.-supported Republic of Vietnam. For most of its existence it operated only as an exile government of sorts, and did not present a challenge to the authority of the existing South Vietnamese government. Backed by the North Vietnamese Communist government, it was intended to assume power following the presumed victory of the Northern forces after the end of the Vietnam War.
These events ultimately did occur, and after the fall of Saigon in 1975, the Republic of South Vietnam assumed power and ruled the South for 15 months.
In July 1976, the Republic of South Vietnam and the Democratic Republic of Vietnam (North Vietnam) were united into the Socialist Republic of Vietnam.