Between July 1, 1980, and April 1, 1985, 118 patients underwent operation for correction of the Wolff-Parkinson-White syndrome. There were 72 male and 46 female patients with ages ranging from 9 months to 70 years (mean 28 ± 6 years). The major indications for operation were medical refractoriness or drug intolerance (60%) and previous cardiac arrest (14%). Associated abnormalities included Ebstein's anomaly (12%), other arrhythmias (34%), coronary artery disease (6%), cardiomyopathy (6%), and congenital heart disease other than Ebstein's anomaly (22%). Two patients had undergone operations for Wolff-Parkinson-White syndrome previously at other institutions. Twenty percent of patients had multiple (two to four) accessory pathways, a total of 149 pathways being present in the 118 patients. Distribution of the accessory pathways was as follows: 58% left free wall, 24% posterior septal, 13% right free wall, and 5% anterior septal. The surgical technique employed previously for the Wolff-Parkinson-White syndrome and for the first 10 patients in the present series was modified in August, 1981, to include (1) 2.5 power optical magnification, (2) exclusive use of the endocardial approach under cardioplegic arrest, (3) wider margins of surgical dissection, (4) sharp dissection of the involved valve anulus, (5) division of only the ventricular insertion of the accessory pathway, and (6) internal identification of the ventricular epicardial peel in all regons of dissection. Of the 149 accessory pathways present, 148 were successfully divided in the 118 patients and, by means of the above modifications, 137 of 137 accessory pathways have been divided successfully in the last 108 patients in the series. The surgical results in these patients document an increase in the success rate for division of accessory pathways from 86% to 99.3%, a decrease in the reoperation rate from approximately 15% to 0%, and a decrease in the incidence of permanent complete heart block from 10.5% to 0.8%. The mortality was 5.0% in the entire series, but only one death occurred following elective operation in the absence of associated cardiac abnormalities (0.8%). Using the present surgical technique, these results suggest that surgical therapy is a conservative alternative to a lifetime of medical therapy in young, otherwise healthy patients with the Wolff-Parkinson-White syndrome.