The article is devoted to the scholarly creativity of the professor of St. Petersburg State University Yury Georgievich Alekseev (1926–2017). Being the apprentice of the well-known Soviet historian I. I. Smirnov, Alekseev became one of the brightest representatives of the St. Petersburg (Leningrad) School of historians — a famous scholar, remarkable lecturer and promoter of historical science. Among his scientific interests one can find the problems of the social, economic and political history of ancient and medieval Russia, the history of Russian legislation, agrarian history, military history, the history of the Navy. The article analyses the work of Yu. G. Alekseev in the connection with the development of the domestic historical science of the 20^th and the beginning of the 21 centuries. Alekseev devoted his books and articles to the agrarian history of Russia, the era of Ivan III and monuments of Russian medieval legislation. In recent years he paid particular attention to the problems of Russia’s military history. All his monographs are closely linked with one another, and all together dedicated to the formation and development of the Russian State. The authors of the article attentively analyze the works of Yu. G. Alekseev, paying close attention to his thorough and subtle work with sources and in-depth knowledge of historiography. The authors compare Alekseev’s views on the evolution of the socio-eco-nomic relations in medieval Russia with I. Ya. Froyanov’s conception of community conception and simultaneously show the connection of these views with the legacy of N. P. Pavlov-Silvansky. Along with other historians of the peasantry, among whom are N. E. Nosov, A. I. Kopanev, I. Ya. Froyanov, A. L. Shapiro, and D. I. Raskin, Alekseev created new theory of the development of Russian peasantry and community during 15^th and 16^th centuries. A main theoretical conclusion of Alekseev is his conceptualization of the medieval Russian state as so called zemsko-sluzhiloie (land-service) State. This theory is a valuable contribution to scholarship. Also of value are his works on the history of national legislation. One can say that his works about the Pskov Judicial Act, Laws of Ivan III, statutory diplomas, his book devoted to the shaping of the Russian administration are the ‘gold standard of national historical scholar’. His contribution to the study of Russia’s medieval military history is multifarious. Alekseev studied the campaigns of Russian troops under the rule of Ivan III and could reveal the large-scale reforms of the Organization of the Office of the military business in Russia of the 15^th and 16^th centuries, particularly, a qualitatively new level of command of the troops. The military victories of Ivan III, the liberation of Russia from the horde’s dependency and the creation of a single State — all these achievements were the result of the above-mentioned great reforms. Refs 62.