The Socialist Republic of Romania (Romanian: Republica Socialistă România, RSR) refers to Romania under Marxist-Leninist one-party Communist rule that existed officially from 1947 to 1989. From 1947 to 1965, the state was known as the Romanian People's Republic (Republica Populară Romînă, RPR). The country was a Soviet-aligned Eastern Bloc state with a dominant role for the Romanian Communist Party enshrined in its constitutions.
The General Secretary during the period was Gheorghe Gheorghiu-Dej.
More information on the Wikipedia page [1].