This study looked at the effect of different appointment time intervals on process and outcome measures in the consultation. Over a five-month period patients attending a two-partner surgery were non-systematically allocated to appointments at five, 10 or 15 minute intervals. Consultations were audiotaped and analysed. When appointments were scheduled at longer intervals, doctors asked significantly more questions and made significantly more statements explaining the problem and its management, while patients asked significantly more questions and made significantly more statements of their own ideas about the problem. In consultations booked at shorter intervals patients were significantly more likely to report in satisfaction questionnaires that they had little or far too little time available. The implications of the results for future planning are discussed.