The aim of the paper is to show the situation of the National Museum Library (NML) in the period of 1939–1945 based on archival documents. Central changes made by the Nazis affected people as well as their work in the NML. It was not possible to continue as before – some employees had been arrested or executed by the Gestapo. Nevertheless, the number of the NML staff increased as a result of the transfer of officials from the closed Ministry of War and Ministry of Foreign Affairs. Two employees of German nationality joined the NML based on the new rules concerning the relations between Czechs and Germans in public services. The operation of the library came under the supervision of Professor Carl Wehmer, who planned a cataloguing reform, was in charge of the book collections and ensured their later evacuation. The plans for a new NML exhibition were cancelled and replaced by propagandistic exhibitions imported from Germany, such as Deutsche Größe. The Nazi ideologists planned to return the National Museum and its library to the original idea of the land museum. Also Emil Franzel, a former leading member of the German Social Democracy in Czechoslovakia, a later member of the Sudeten German Party and in 1940–1941 an official in the NML, followed the idea of a land museum in his book History of the National Museum Library (Prague 1942), the first monograph on the history of the NML.