This paper presents an exchange of letters between the Polish-Scandinavian Research In stitute in Copenhagen and the Polish hero Jan Karski, Washington, DC. The Institutein Copenhagen, represented by its director (Eugeniusz S. Kruszewski), scientific secretary (Józef Parnas) and members of the management (Tadeusz Głowacki, Jørgen Mogensen), began to correspond with Jan Karski in 1986, and received a final letter from him in 2000. The main object of the correspondence was cooperation with the Polish-Scandinavian Research Institute in the area of World War II and the extermination of Jews in German-occupied Poland. We mediated between people from Germany, France, Great Britain and the USA who expressed their opinions about the Claude Lanzmann movie „Shoah”, and World War II reality in Poland during German occupation. Jan Karski visited Denmark and Sweden in 1988, and his lectures and interviews were very successful. It was a very fruitful collaboration