This article is the first attempt to present a biography of Mieczysław Fejgin (1894– 1975), a doctor of Bolesław Bierut. Fejgin came from a fairly wealthy Jewish family living in Wola Krzysztoporska. In 1913, he began medical studies in Bordeaux, France, which were interrupted by the outbreak of the First World War. He obtained his diploma in 1922 at the Medical Faculty of Warsaw University. In 1918, Fejgin volunteered for the Polish Army, and was awarded the Commemorative Badge of the LithuanianBelarusian Front for participating in the Polish-Bolshevik war. In the inter-war period, he first worked at the Wolski Hospital as an assistant to the eminent doctor, Prof. Anastazy Landau, and then from 1931 until the outbreak of the war, he headed an internal department at the Orthodox Church Hospital in Warsaw. Back then he gained a reputation as an excellent doctor, an author of numerous articles also published in foreign journals. Fejgin participated in the September campaign and then moved to Białystok. He worked as an internist consultant in a Soviet military hospital until June 1940. The period from July 1940 to January 1942, along with other exiles, Fejgin spent in a labour camp located in the Arkhangelsk Oblast, from which he was released under the amnesty in 1942. Then, until the moment of leaving the USSR in January 1945, Fejgin worked in a municipal polyclinic in Soroczyńsk. Simultaneously, he was an active 298II. Varia member of a local branch of the Union of Polish Patriots. Along with the Second Polish Army, he took part in the Lusatian offensive (as an internist at the Field Evacuation Point). After the end of the war, he found employment at the Ministry of National Defense hospital in Warsaw, and headed a department of internal diseases at the Ministry of Health Clinic. In the years 1948–1956, he was Bolesław Bierut’s doctor. In 1954 he became the Chief Internist of the Polish Army in the rank of colonel. After his release from active military service, Fejgin became the head of department at the Czerniakowski Hospital in Warsaw, and at the same time was an internist and consultant at the Ministry of Health Clinic. Mieczysław Fejgin proved to be an outstanding specialist, especially in the field of heart diseases.