Patients with supraventricular reciprocating tachycardias or atrial fibrillation with rapid ventricular response mediated over an accessory pathway may be difficult to treat. In cases of medically refractory arrhythmias, or in patients requiring operations for other cardiac abnormalities, surgical division of an accessory pathway was attempted in 18 consecutive patients. The major indication for operation was drug refractory tachyarrhythmias in 13 patients, whereas 5 patients were operated upon primarily because of either aortic or mitral or tricuspid valve replacement. After careful preoperative and intraoperative electrophysiological evaluation, all patients revealed only one bypass tract. The location of the accessory pathways were as follows: 16 left free-wall and 2 right free-wall. Surgical division was attempted using the "Sealy-Technique". 14 accessory pathways were divided successfully and in 2 patients they were made responsive to previous ineffective medical therapy. In one patient operation was unsuccessful. In 3 patients reoperations were necessary because of the reappearance of accessory pathway conduction. One patient with associated Ebstein's anomaly died intraoperatively. During a follow-up of 26 +/- 21 months, 14 patients were free of tachyarrhythmias without antiarrhythmic medication, whereas 2 patients responded to previously ineffective therapy. Another patient undergoing unsuccessful surgical ablation was treated with amiodarone. These results indicate that by employing the Sealy-Technique accessory pathways could be successfully divided in 14 of 18 patients (78%) and additionally made responsive to previously ineffective antiarrhythmic therapy in 2 patients (11%) (total success = 89%).