Bonifica umana. La clinica dell’uomo nuovo - The author studies the anti-Semitism of the 1930s, and highlights the continuity between past anti-Jewish discrimination and modern anti-Semitism. He points out how biomedical disciplines and psychiatry include secularized anti-Jewish attitudes. Moreover, he underlines that Nazi and fascist anti-Semitism draws on a century of research on differential assessment of individuals (based on moral and attitudinal features) and on racial degeneration. Bio-medical knowledge has recoded modern racism, developing a scientific device for social prophylaxis that differentiates good races from bad races, and condemns the latter to death. The goal of the reclamation of man becomes therefore a therapeutic act , the disinfection of society. Keywords: anti-Jewish discrimination, anti-Semitism, Nazism, fascism, psychiatry.