In 1932 Gross became leader of the National Socialist German Doctors' Alliance. The following year he was appointed by Adolf Hitler as head of the Reich Bureau for Enlightenment on Population Policy and Racial Welfare. In 1936 he was elected to the Reichstag where he expressed fanaticalanti-semitic views.
Considered to be an expert on the subject of racial purity, Gross became head of NSDAP Racial Policy Department in 1942. A supporter of the Final Solution Gross told one meeting that: "As far as the historical appearance of the Jew in Europe is concerned, we believe that the hour of his death has irrevocably arrived." Walter Gross died in 1945.