The standard of professional candour with patients has undergone a significant change over the past 30 years. Independent of their obligation to disclose information necessary for informed consent, physicians are increasingly expected to communicate important information to patients that is not immediately related to treatment decisions. The purpose of truth telling is not simply to enable patients to make informed choices about health care and other aspects of their lives but also to inform them about their situation. Truth telling fosters trust in the medical profession and rests on the respect owed to patients as persons. It also prevents harm, as patients who are uninformed about their situation may fail to get medical help when they should.