Historical views of the patient-physician relationship assumed that the physician's role was to act in the best interests of the patient and to direct care and make decisions about treatment on the patient's behalf. However, under current legal and ethical principles, beneficence is no longer sufficient; respect for autonomy is paramount, necessitating patient participation. None the less, physicians question whether patient participation is realistic in actual clinical situations. This first of two articles reviews models of the patient-physician relationship and the literature about barriers to participation, the effect of participation on patient outcome and the extent to which patients want to be informed. The image of a dependent patient who prefers to be sheltered from harsh truths is not supported. It appears that most patients wish to have information, although there is an identifiable proportion who do not. To be understood, health information must be presented in a way that is appropriate to the patient. Format, content and timing of the material are all important. Mechanisms for incorporating such information into busy clinical practices are crucial.