OBJECTIVE To determine the need for long-term pacing and optimum mode of pacing in cardiac transplant recipients. METHODS (a) A retrospective review of patient records. (b) A prospective study of pacemaker use by 24 hour ambulatory electrocardiography before and after reprogramming to minimise use of pacemakers. METHODS Outpatient clinic, supra-regional cardiopulmonary transplant unit. METHODS All 21 patients at this centre who had received permanent pacemakers after cardiac transplantation. 18 of 19 survivors completed the prospective part of the study. METHODS The presence of pacing during a 24 hour ambulatory electrocardiographic recording (programming: 50 beats/min, rate sensor inactivated). RESULTS 21 of 191 (11%) recipients surviving one month or more received permanent pacemakers. The indication was sinus node dysfunction in 13 (62%) and atrioventricular (AV) block in eight (38%). Patients who paced on follow up 12 lead electrocardiograms declined from 38% at three months to 10% at three years after transplantation. After programming to 50 beats/min only five of 18 (28%) patients paced during a 24 hour ambulatory recording. Four of 11 (36%) recipients who received pacemakers for sinus node dysfunction paced compared with one of seven patients (14%) paced for AV block. No patient who had a pacemaker before the 16th day after operation continued to pace whereas five of nine implanted later were used long-term. CONCLUSIONS Only five of 18 (28%) patients with pacemakers continued to pace long-term. Continued pacing was more common in those with persistent sinus node dysfunction after the second week after operation but the need for long-term pacing was not predictable.