A significant portion of the practice of medicine is dependent on individual acts of medical altruism. Many of these acts, such as the donation of blood, gametes, stem cells, and organs, entail varying degrees of bodily intrusion and, for the altruist, various combinations of discomfort, risk, and expense. Discussion of the ethics of altruism has typically been fragmented under various rubrics such as blood donation, organ and tissue transplantation, health information, and the assisted reproductive technologies. The ethics of these specific examples of altruism are best explored in conjunction with a broader discussion of their relatively neglected mother discipline, altruism in medicine. Copyright © 2010 Cambridge University Press.