Electrocautery, commonly used during surgery to maintain hemostasis, can have significant detrimental effects in the paced patient. Damage to the pulse generator, reprogramming of the pacemaker, changes in the capture threshold, and ventricular fibrillation can all be induced by electrocautery. Familiarity with the particular pacemaker in use is critical in minimizing these adverse effects. Preoperative evaluation of the patient's dependence on the pacemaker and evaluation of pacemaker function should be performed and documented. We recommend close intraoperative monitoring of heart rate and rhythm, and suggest that a pacemaker programmer be on hand in the surgical suite during the operation. A postoperative check of pacemaker function should be carried out so that electrocautery-induced pacemaker malfunction will not go unnoticed or uncorrected. Three cases are presented which clearly illustrate these points.