The subject of this article is the interpretation of Italian fascism and German National Socialism up to 1939 presented in the scientific works of Andrzej Mycielski, professor of constitutional law at the Stefan Batory University in Vilnius. This constitutionalist from Vilnius made a very interesting and insightful interpretation of Italian fascism–its origins, the legal basis for the functioning of the state, and its economic policy. Italian fascism appeared to him as a movement opposed not only to communism, but also to parliamentary democracy and liberalism, and yet containing valuable elements. Mycielski’s views on German National Socialism, on the other hand, were characterised by a greater distance from the totalitarian system of the Third Reich.