There are few data available on which to base recommendations for effective communication in the cancer consultation. This paper describes a computerised interaction analysis system designed specifically for the cancer consultation and its application in a study investigating the relationship between doctor-patient behaviour and patient outcomes. One hundred and forty-two cancer patients attending their first consultation with a cancer specialist were audio taped and a copy of the tape was retained for interaction analysis. Before the consultation patient anxiety and information and involvement preferences were measured. Outcomes included recall of information, patient satisfaction with the consultation and psychological adjustment to cancer. Doctor behaviour was shown to vary significantly according to the age, sex, involvement preferences and in/out-patient status of the patient. The ratio of doctor to patient talk was related to satisfaction with communication, while patients whose questions were answered showed better psychological adjustment at follow-up. The results suggest that patient-centred consultations lead to improved satisfaction and psychological adjustment. These data provide precise information about consultation behaviour which can be used in the documentation of current practice and the evaluation of new interventions to improve communication.