Background: Disregard of Hippocratic medical ethics by major leaders in the Public Health establishment and the leadership role played by physicians during the Nazi era in Germany (1933-1945) pose continuing challenges for later generations to investigate and disclose. Aims: We review the history of evolution from humiliation of mental patients, other ill and disabled individuals and targeted ethnic groups to humiliation, sterilization, and "involuntary euthanasia" (a euphemism for medical murder). We focus on the role played by psychiatrists and neurologists during the Nazi period in Germany; we discuss the ethical norms of universal dignity, compassion and responsibility and we propose concrete steps to prevent recurrence of medically supported genocide. Methods: We explored the history of psychiatry of the period leading up to, including and immediately after the Nazi era in order to analyze the ethical standards and practices of psychiatrists and neurologists. Results: Psychiatrists, and neurologists, were guilty leaders and participants in the implementation of the Nazi programs, which escalated from humiliation and classification of their victims to the exclusion of the mentally ill and disabled, to devaluation and forced sterilization, to medical murder, then finally to the industrialized mass murder of millions, named the "Final Solution".