This study deals with the heretofore unknown activity of Leoš Janáček at the two main museum institutes in Brno. It asserts that from ca. 1888 until the end of his life, Leoš Janáček was a member of the Brno Museum Association, and it also makes reference to previously unknown sources from scholarly literature to which he had access as a member of the association. A surprising discovery is that the composers participation in the German-Czech Moravian Museum Society from 1900 was connected with the creation of the first collection of Moravian composers manuscripts (1903) and with an attempt to obtain financial support from the Provincial Committee for a printed edition of works by Moravian composers. We thus get a more complete picture of Janáčeks interactions and contacts in the environment of the Czech and German intellectuals who surrounded him and of the composers involvement in professional activities., Jarmila Procházková., Obsahuje seznam literatury, Rubrika: Studie, and Anglické resumé na s. 350.