The Party of Democratic Socialism (Czech: Strana demokratického socialismu) is a democratic socialist political party in the Czech Republic. It is a founding member party of the Party of the European Left.
The party has its name since December 1997. It's the political unification of SDL (Party of the Democratic Left) and LB (Left Block) that took place in June 1997. In the beginning the party had the name LB-SDL.