The Socialist Republic of Romania was a Marxist–Leninist one-party socialist state that existed officially in Romania from 1947 to 1989. From 1947 to 1965, the state was known as the Romanian People's Republic. The country was an Eastern Bloc state and a member of the Warsaw Pact with a dominant role for the Romanian Communist Party enshrined in its constitutions. Geographically, RSR was bordered by the Black Sea to the east, the Soviet Union to the north and east, Hungary and Yugoslavia to the west, and Bulgaria to the south.

A socialist state, socialist republic, or socialist country, sometimes referred to as a workers' state or workers' republic, is a sovereign state constitutionally dedicated to the establishment of socialism. The term communist state is often used synonymously in the West, specifically when referring to one-party socialist states governed by Marxist–Leninist communist parties, despite these countries being officially socialist states in the process of building socialism and progressing toward a communist society. These countries never describe themselves as communist nor as having implemented a communist society. Additionally, a number of countries that are multi-party capitalist states make references to socialism in their constitutions, in most cases alluding to the building of a socialist society, naming socialism, claiming to be a socialist state, or including the term people's republic or socialist republic in their country's full name, although this does not necessarily reflect the structure and development paths of these countries' political and economic systems. Currently, these countries include Algeria, Bangladesh, Guyana, India, Nepal, Nicaragua, Sri Lanka and Tanzania.