The ethics of experimentation on human subjects has become the subject of much debate among medical scientists and philosophers. Ethical problems and conflicts of interest become especially serious when research subjects are recruited from the class of patients. Are patients who are ill and suffering in a position to give voluntary and informed consent? Are there inevitable conflicts of interest and moral obligation when a personal physician recruits his own patients for an experiment designed partly to advance scientific knowledge and (...) only partly as therapy for those patients? The views of the eminent American ethicist Hans Jonas on these issues are briefly summarised and criticised, and some moral guidelines are then proposed to regulate experimentation on human subjects. (shrink)