In most cases, patient preferences are crucial in making good health care decisions. For example, choices between chemotherapy and radiation treatment usually hinge on trade-offs that only patients can decide about. In recognition of the importance of patient preferences in clinical decisions, health services researchers have begun developing decision aids to help patients understand complex medical information. But these decision aids might lead to "bad choices"-choices that are inconsistent with people's stated preferences. In this paper, the author provides examples of how people make inconsistent medical decisions, and briefly discusses future directions for exploring ways of structuring information so that patients are less likely to make inconsistent choices.