Revolutionary Party of the Nationalist Left

The Revolutionary Party of the Nationalist Left (Spanish language: Partido Revolucionario de la Izquierda Nacionalista, PRIN) was a left-wing political party in Bolivia. It was founded in 1963 by the labor leader Juan Lechín when leaders of the Revolutionary Nationalist Movement (MNR) did not nominate him for president. The PRIN combined the left wing of the MNR (including future president Hernán Siles Zuazo) and former members of the Revolutionary Workers' Party (POR).

After the military coup of 1964, the PRIN was forced underground. Many of its members, including Siles, returned to the MNR. It was also weakened because Lechín was deported to Paraguay by the military junta. After 1971, its position as the main party to the left of the MNR was supplanted by a new party formed by Siles, the Revolutionary Left Movement (MIR). The party was once again suppressed in the 1970s by the military under the presidency of Hugo Banzer.

Following the end of military rule in 1979, a member of the PRIN, Lidia Gueiler Tejada, was appointed interim president. Gueiler is the only ever to serve as president in Bolivia.

In the 1980s the strength of the PRIN declined further, in part because of the rising fortunes of Siles' MIR.