Randomized clinical trials can present a scientific/ethical dilemma for clinical investigators. Statisticians have tended to focus on only one side of this dilemma, emphasizing the statistical and scientific advantages of randomized trials. Here we look at the other side, examining the personal care principle on which the physician-patient relationship is based and observing how that principle can make it difficult or impossible for a physician to participate in a randomized clinical study. We urge that the view that randomized clinical trials are the only scientifically valid means of resolving controversies about therapies is mistaken, and we suggest that a faulty statistical principle is partly to blame for this misconception. We conclude that statisticians should be more sensitive to the physician's responsibility to the individual patient and should, besides promoting randomized trials when they are ethically and practically feasible, work to improve the planning, execution, and analysis of nonrandomized clinical studies.