It is well-known that from 1963 Helmut Bauer was head of the department of neurology at the University of Göttingen and was one of the German pioneers in research into multiple sclerosis. During the years 1971-1972 he acted as president, later honorary president of the German Neurological Society (DGN), of which he also became honorary member in 1982. Almost unknown, however, is his career during the "Third Reich" and immediately after the war. After returning from the USA in 1932, he completed his medical studies in the German Reich. In 1940 he again acquired German citizenship, which has to be interpreted as an acknowledgement of the Nazi regime. He was initially active in the Foreign Department of the Reich Medical Council. In 1941 he joined the SS and served as member of the so-called Künsberg special commandos of the SS in France, Greece, and Italy as well as in the Baltic states and the Soviet Union (1941-1943). As a medical case officer, he was in charge of the confiscation of medical material and documents, even of healthcare institutions and of Jewish property. In 1943 and 1944 he worked as SS Captain (Hauptsturmführer) at the Research Center for Medicine in Foreign Countries and Settlement Biology and the Institute for Microbiology at Sachsenburg Castle near Frankenberg in Saxony, a joint establishment of the Wehrmacht, the Ministry of the Interior and the Robert Koch Institute in cooperation with the SS. In addition to the search for a vaccine against Yersinia pestis and the participation in war propaganda, Bauer's research unit was mainly concerned with the statistical evaluation of "racial examinations" of resettlers. After a short time as a prisoner of war (POW), Bauer had to undergo a denazification trial where he succeeded in being exonerated enabling him to pursue his medical career. Recent historical investigations have revealed that he was involved in military and racial hygiene (eugenics) crimes of the Nazis and therefore belonged to the group of persons who were active supporters of the political system.