The history of ‘electroshock therapy’ (now known as electroconvulsive therapy (ECT)) in Europe in the Third Reich is still a neglected chapter in medical history. Since Thomas Szasz’s ‘From the Slaughterhouse to the Madhouse’, prejudices have hindered a thorough historical analysis of the introduction and early application of electroshock therapy during the period of National Socialism and the Second World War. Contrary to the assumption of a ‘dialectics of healing and killing’, the introduction of electroshock therapy in the German Reich and occupied territories was neither especially swift nor radical. Electroshock therapy, much like the preceding ‘shock therapies’, insulin coma therapy and cardiazol convulsive therapy, contradicted the genetic dogma of schizophrenia, in which only one ‘treatment’ was permissible: primary prevention by sterilisation. However, industrial companies such as Siemens–Reiniger–Werke AG (SRW) embraced the new development in medical technology. Moreover, they knew how to use existing patents on the electrical anaesthesia used for slaughtering to maintain a leading position in the new electroshock therapy market. Only after the end of the official ‘euthanasia’ murder operation in August 1941, entitled T4, did the psychiatric elite begin to promote electroshock therapy as a modern ‘unspecific’ treatment in order to reframe psychiatry as an ‘honorable’ medical discipline. War-related shortages hindered even the then politically supported production of electroshock devices. Research into electroshock therapy remained minimal and was mainly concerned with internationally shared safety concerns regarding its clinical application. However, within the Third Reich, electroshock therapy was not only introduced in psychiatric hospitals, asylums, and in the Auschwitz concentration camp in order to get patients back to work, it was also modified for ‘euthanasia’ murder.