During the war, Gebhardt conducted medical and surgical experiments on prisoners in the concentration camps at Ravensbrück (which was close to Hohenlychen Sanatorium) and Auschwitz.
In order to absolve Gebhardt for his failure to prescribe sulfonamide for Heydrich, Himmler suggested to Gebhardt that he should conduct experiments proving that sulfonamide was useless in the treatment of gangrene and sepsis.