He studied medicine first at Bonn, later at Berlin and Leipzig, and finally graduated in Hamburg in 1938.

He joined the SS in 1934 (ultimately reaching the rank of Sturmbannführer [major]) and became a member of the NSDAP in June 1937.

On 1 November 1939, he was assigned to the Waffen-SS of the SS-Department of the Hohenlychen Sanatorium as a physician and SS Second Lieutenant.

[citation needed] In 1940, he became troop physician of the SS Division Leibstandarte Adolf Hitler.

Fischer subsequently regained his license to practice medicine and started a new career at the chemical company Boehringer in Ingelheim, where he stayed until his retirement.