Poland was divided among two nations the Nazi Reich and the communist Soviet Union in 1939. The situation in occupied territories (General Gouvernement) differed from the situation in the territories annexed by the USSR and the Third Reich; in those territories slightly different laws were in force. However, to simplify the text the authors shall use the term “occupation” for those two forms. There was a one-party regime there; the almighty security apparatus (in Germany – the RSHA, and fi rst of all Gestapo, and in the USSR – the NKVD) with a network of agents (which in the USSR was perfectly developed) imposed obedience towards the authorities. The national socialist policy interfered in all spheres of public life. Stalin in a regular manner liquidated real and imaginary enemies. Such a blind terror directed at one’s own nation – with the exclusion of the so-called enemies of the Reich that is to say political enemies, Jews, Poles – was not present in Germany. As late as February 1945 the summery police courts were established for German civilians which was connected with the attempts aimed at stopping defeatism. Apart from that the courts dealt with the desertion-related trials. Casualties connected with direct and indirect extermination are formally set at the level much higher in the case of the activities of German authorities (over 5 million people) than in the case of Soviet activities (from 500 000 up to 1 million), but in the case of the losses incurred by the Polish landed gentry the situation is much different as the proportions are the following: 50.75 per cent were killed by Soviets and 40.57 per cent killed by Germans. However, these data are only partially trustworthy and reliable. No detailed research has been carried out into the losses incurred under the Soviet occupation so far due to the lack of access to the sources. 250 000 Poles conscripted to the Red Army by force were not taken into account, similarly as about half a million refugees from the western territories of the Second Republic of Poland or rank and fi le soldiers of the Polish Army taken captive in September 1939. Both Nazism (including fascism) and Soviet communism glorifi ed violence, authority, force of will and war as methods of dealing with all sorts of problems. According to historians (however, not all) both regimes are comparable. Yet, there is a question whether the Holocaust (similarly as the extermination of Gypsies or Polish intelligentsia) were the exceptional phenomena in the history of a humankind. Can this term be used in reference to the communist regime? The greatest accumulation of Nazi and communist crimes took place in 1930s and 1940s that is to say the period of occupation of Polish territories. People believe that Stalinist crimes were the tool of terror aiming at achieving political and social goals, whereas the extermination done by Nazi was the goal itself, but the phenomenon of genocide was nothing new in the history. The article touches upon the problem of collaboration of Poles with occupiers as well. Although under the German occupation the problem was rather marginal or the cooperation was ineffective, under the Soviet occupation it was much more widespread and resulted in taking over the power by the Polish ‘Quisling’ that is it led to the rule of Bolesław Bierut.