What do we mean by the frequently invoked yet seldom questioned »physician‹s responsibilty»? This study, which was awarded the Stehr-Boldt Prize by the University of Zurich, attempts to define this more closely for the physician in his real work as part of the diagnostic-therapeutic process. Why has the term »physician‹s responsibility» replaced the traditional term "physician‹s obligations»? Is the physician primarily responsible for his patient or even for the health of the entire population? What responsibility is a result of the constitutive precariousness of the medical profession, in which there is no guarantee of success or of the absence of undesirable side effects? Is it possible to obtain guidance in dealing with controversial issues such as abortion or euthanasia by examining the physician‹s responsibility?