There is currently substantial disagreement about the kind of information that must be disclosed in obtaining an informed consent. This study examined physicians' interpretations of the demands of two alternative legal standards for disclosure, as well as a third standard intended to capture their normative sense of what should be disclosed to patients. Other factors which might affect disclosure practices of physicians were also studied. The findings raise questions about the extent to which a legal standard for disclosure can have an impact on medical practice; the data suggest that doctors currently disclose what they think patients want to be told. However, it appears that physicians substantially underestimate the amount of information patients wish to receive.