The importance of living organ donation is increasing worldwide. The possibility of helping a sick person by donating their own healthy organ forces relatives and friends to make critical, value-related life decisions. According to the German Transplantation Act, the removal of an organ from a living person is only permitted if the decision of the organ donor was made voluntarily. But what does voluntariness mean in the context of living organ donation and what does it mean, conversely, to deny a person the ability to self-determination? The authors illuminate these questions from a psychological, legal, philosophical and medical-sociological point of view. Other co-authors are the sociologist Christiane Gross (Munich) and the psychologist Ursula Sedlmayer (Munich).