Parliamentarians from across Europe have condemned the crimes committed under communism.
Russian communists still honour Lenin every year
The Council of Europe's parliamentary assembly said it "strongly condemned the massive human rights violations" committed in the old Soviet bloc.
The council - a European human rights watchdog - has 46 member states. Its parliamentary assembly meets four times a year to debate human rights issues.
Communists and many socialists in the assembly opposed the resolution.
The resolution called on all communist or post-communist parties among the member states to condemn past communist abuses "without any ambiguity".
Goran Lindblad, an MP of the conservative Swedish Moderate Party and leading voice behind the resolution, told the BBC that "the purpose is to give moral restitution to those victims who suffered under communist regimes".
He said: "It's also very important to have an awareness campaign, so people will never repeat this mistake.
"If you go to a regular school in my country, for example, and ask the children, they don't know anything about the Berlin Wall."
Tougher proposals calling for official government condemnations of communist crimes and fresh investigations into such crimes failed to win enough support.