Failure to keep appointments is disruptive to the health care delivery system in several ways. Rates of missed appointments in a variety of practice settings demonstrate a significant problem. The patient most likely to fail to keep a given appointment is one who is young, comes from a low socioeconomic group, has a large, unstable family, and has previously broken appointments. In addition, this patient will most likely have no significant ongoing relationship with a single physician, may have been referred from an emergency room, will have been scheduled for his or her appointment at a distant time, may well have forgotten about the appointment or thought it was scheduled for another time, and will feel little sense of urgency about keeping the appointment. Several effective methods to reduce appointment-breaking behavior are discussed. Mailed appointment reminders are both effective and cost-efficient. Improved communication between patient and physician combined with personal interest and attention an produce a positive effect on the appointment-keeping behavior of a patient. Finally, the pragmatic details of appointment scheduling can be altered to reduce the disruptive effect of the missed appointment by such methods as predictive overbooking based on individual patient characteristics, use of the modified wave scheduling technique, and elimination of the automatic reappointing of patients who have previously broken appointments.