In the interwar period the eugenic ideas gained the status of a scientific theory and become attractive to a wide range of physicians. Among them were doctors of Jewish origin who perceived eugenics as a tool in the fight for biological rebirth of the Jewish nation. Polish-Jewish psychiatrist Raphael Becker (1891–1939?), the author of dozens of scientific papers, was the most famous eugenist among Jewish psychiatrists, not only in Poland but also in Europe. After graduation in medicine at the University in Zurich and training in the psychiatry clinic Burghölzli under the guidance of Eugen Bleuler, Rafał Becker became interested in the question of epidemiology of mental disorders among the Jews. In the interwar period, dealing with the statistics of mental disorders among Polish Jews, and directing a psychiatric hospital “Zofiówka” in Otwock, he significantly contributed to the development of medical care for the mentally ill Jews in Poland. Becker’s scientific ideas were greatly influenced by the work of Alfred Adler and Ernst Kretschmer. The article presents the life and scientific achievements of Becker, with particular emphasis on his views on eugenics.