The article is devoted to understanding of the contribution of the Czech scholar Jan Slavík (1885—1978) to the study of Soviet history, especially the revolutionary events of 1917 and the biography of V.I. Lenin. The methodological views of J. Slavík, which led him to research Modern history, are analyzed in the article. The relations of J. Slavík with the Russian emigration, especially during his work in the Russian foreign historical archive, received special attention. The reasons for which during the lifetime of the historian his scientific work turned out to be without due attention, are explained. At the same time, the conclusion is drawn that J. Slavík's research on Soviet history was ahead of his time in many respects.