Double genocide theory is a term used to refer to the claim that the atrocities committed by the Soviet Union against Eastern Europeans constitute a genocide that was equivalent in scale and nature to the Holocaust, in which approximately six million Jews were systematically murdered by Nazi Germany. The theory first gained popularity in Lithuania after the fall of the Soviet Union in 1991, particularly with regard to discussions about the Holocaust in Lithuania.
A more extreme version of the theory vindicates the actions of local Nazi collaborators as retaliatory by accusing Jews of complicity in Soviet repression, especially in Lithuania, eastern Poland, and northern Romania. Scholars have criticized the double genocide theory as a form of Holocaust trivialization.