1989–1991: Workers' Party of Spain–Communist Unity (in Spanish: Partido de los Trabajadores de España–Unidad Comunista) was a communist political party in Spain, founded by Santiago Carrillo and his followers after their expulsion from the Communist Party of Spain (PCE) in October 1985.

Initially, the party was known as Communist Party of Spain (Revolutionary Marxist) (Partido Comunista de España (Marxista-Revolucionario)), a name still registered at the election authorities,[4] and related to the line of Carrillo in the PCE throughout the 1970s, as the party ideology of PCE under his leadership was redefined from Marxism-Leninism to Revolutionary Marxism.

PTE-UC participated in the 1986 general election with the candidature Communists' Unity Board (Mesa para la Unidad de los Comunistas), which gathered 229,695 votes (1.1%).

Carrillo stood as a candidate for the European Parliament election of 1987, and got 222,680 votes (1.1%).

Following the result, PTE-UC merged into the Spanish Socialist Workers' Party in 1991, and organized itself as an internal tendency called Left Unity (Unidad de la Izquierda).