Alfred Grotjahn (25 November 1869 – 4 September 1931) was a German physician, social hygienist, eugenicist, journalist-author and, for three years between 1921 and 1924, a Member of the Reichstag (national parliament) in the recently launched German republic. He became celebrated as a pioneer, and among admirers an inventor, of the discipline of "social hygiene" which, in Germany, was not merely an ephemeral euphemism for the sociological study of sexually transmitted diseases, but embraced a series of topics along the interface between sociology and medicine. When first he publicised his ideas at the start of the twentieth century he encountered a barrage of opposition from the powerful and increasingly politicised Eugenics lobby, but during the next three decades some of his own thinking