In order to evaluate the quality of an informed consent procedure (I.C.P.) 48 patients with advanced cancer were offered participation in a phase I clinical trial and entered an I.C.P. consisting of three separate conversations. In the first session, the possible risks and benefits of a phase I study were informally explained by the patient's personal physician. The second session was attended by the patient, a relative, a registered nurse and a physician; the third session was held at least 5 days after the second. Forty-one patients gave their consent motivated by hope for improvement of their conditions, pressure exerted by relatives and friends, the desire to contribute to the progress of medicine or simply because they felt they had 'no choice'. Encouragement by relatives or friends seems to be a powerful incentive to participate. A period of a few days to consult relatives, friends or trusted physicians as a part of the procedure seems helpful in arriving at a well-considered decision.