Psychiatrist Thomas Szasz fought coercion (compulsory detention) and denied that mental illness existed. Although he was regarded as a maverick, his ideas are much more plausible when one discovers that between 1939 and 1941, up to 100 000 mentally ill people, including 5000 children, were killed in Nazi Germany. In the course of the Nazi regime, over 400 000 forced sterilisations took place, mainly of people with mental illnesses. Other countries, including Denmark, Norway, Sweden and Switzerland, had active forced sterilisation programmes and eugenics laws. Similar laws were implemented in the USA, with up to 25 000 forced sterilisations. These atrocities were enabled and facilitated by psychiatrists of the time and are only one example of the dark side of the profession. This article reviews some of these aspects of the history of psychiatry, including Germany's eugenics programme and the former USSR's detention of dissidents under the guise of psychiatric treatment.