The monograph examines the figure of Nikolai Kostomarov as a Ukrainian historian, writer and public figure. An analysis of modern Ukrainian historiography has been carried out, which covers the scientific, journalistic and social activities of the scientist, taking into account his Ukrainocentric position. Considerable attention is paid to the interdisciplinary discourse of domestic bone marrow studies. Nikolai Kostomarov's views on key issues of Ukrainian history and culture are highlighted. The scientific work of a scientist is considered in the light of sources of personal origin.