The aim of the article is to analyze the activity of mufti Jakub Szynkiewicz (Yakub Shinkevich) during the Second World War. The author of the article shows that there is no evidence of the existence of military units consisting of Tatars (inhabiting the lands of modern Belarus), which were a part of the units of the German armed forces. However, we could find some data on the cooperation of individual Tatar representatives with Wermacht and SS, as well as their participation in political collaboration. Mufti Szynkiewicz turned out to be one of the collaborators. Szynkiewicz became the representative of all Muslims in the territories occupied by the Nazis to the east of the General Gouvernement and East Prussia. His activity was supported by such Tatar-Muslim leaders as Ali (Aleksander) Smajkiewicz, Bary Chalecki and Husejn Jakubowski. Muslim leaders appointed Tatar committees in order to select the Tatars showing loyalty towards the Nazi authorities and to organize activities to preserve national traditions and the Islamic religion. According to information taken from the data of the National Archives of the Republic of Belarus, at the end of February 1944 there were three committees: in Minsk, Kletsk and Lakhovichi. In addition, another goal of the muftiat was to establish the Tatar Youth Organisation. Mufti Szynkiewicz’s ap peals addressed to the occupation authorities with a request for permission to form a Muslim youth association, received positive feedback. An agreement on this matter was reached in February 1944. The meeting at which establishing the Tatar Youth Organisation was officially announced took place in Alytus, Lituania on May 19, 1944, where the Mufti spoke with the welcome speech. Analyzing the source materials, the author of the article concludes that during World War II massive Tatar cooperation from the areas of contemporary Belarus with the German occupation authorities could not be observed, and the attempts of ideological mobilization of Tatars to collaborate, undertaken by some Muslim leaders with mufti Szynkiewicz, did not bring significant results.