Introduction. The article considers the problem of the soviet tankers participation in the Spanish Civil War in its initial period. Methods and materials. The study is based on documents of the Intelligence Directorate of the People’s Commissariat of Defence of the Soviet Union. They became available after the publication of the first three volumes of the eight serial edition “Red Army and the Spanish Civil War (1936– 1939)”. Analysis. It is emphasized that the first group of Soviet tankers arrived in Spain on October 13, 1936, together with a batch of T-26 tanks (50 in total). On October 29, a tank company, which in a short time prepared the missing crew members from among the Spaniards, took part in a combat offensive operation in the Madrid area. According to documentary evidence the effectiveness of the combat use of tanks was minimal and was a result of the unwillingness and inability of the Spanish infantry, including its command staff, to act together with tanks. The documents characterize the T-26 tank as a reliable, hardy, easy-to-handle vehicle, superior in all technical characteristics to light tanks of German and Italian production, but with unsuccessful turret geometry, with weak armor, with an imperfect design of the turret swivel mechanism, with an unusable radio antenna. The article considers presented in the documents problem of the moral, political, psychological and physical condition of soviet tankers in Spain. The documentation also notes high level of military discipline, gives examples of heroic deeds of tankers, primarily members of the All-Union Communist Party (Bolsheviks). At the same time attention is drawn to cases of excessive caution of individual commanders bordering on cowardice. An important place in the documents is given to the physical condition of tankers who find themselves in unfamiliar climatic and social conditions as well as in terms of a completely different food ration. It is noted that almost 100% overwork of personnel associated with continuous participation in hostilities, accompanied by various diseases. Results. The article emphasizes the importance of the direct participation of Soviet tankers in the hostilities of 1936–1937. It made it possible to prevent the military defeat of the Spanish Republic at the stage of creating a regular People’s Army. Key words: Spanish civil war, soviet military aid, tanks, tankers, combat activity, overwork, diseases.