K. A. Fedin’s diaries related to the time of the intense activity of the literary community “Serapion brothers” (1921–1924) have not been preserved. Therefore, the material for the studies of the life of the group as well as of its separate members is obtained by the researchers in the epistolary legacy of the writer. The researchers hardly ever refer to the diaries of the later period, apparently believing that Serapion brothers entirely disappeared from the literary life after 1929.