In the United States and Germany before World War II, physicians participated in state-authorized eugenic sterilization programs in an attempt to prevent persons deemed to possess undesirable heritable characteristics from propagating. A comparison of U.S. and German histories reveals similarities that argue against easy dismissal of a Nazi analogy. On the basis of a review of editorials in The New England Journal of Medicine and Journal of the American Medical Association from 1930 to 1945 it is difficult to accept the suggestion that the alliance between the medical profession and the eugenics movement in the United States was short-lived. Comparison of the histories of the eugenic sterilization campaigns in the United States and Nazi Germany reveals important similarities of motivation, intent, and strategy and differences that explain why support for eugenic sterilization in the United States gradually weakened. The eugenics movement in Germany was influenced by economic crisis, radical nationalism, Hitler's totalitarianism, and the medical profession's willing participation and attraction to Nazism for financial and ideological reasons. In the United States, a combination of public unease, Roman Catholic opposition, federal democracy, judicial review, and critical scrutiny by the medical profession reversed the momentum of the eugenics movement and led to the conclusion that eugenic sterilization should be voluntary.