Ebstein"s anomaly is the most common congenital heart disease associated with the Wolf-Parkinson-White syndrome. Between November 1973 and March 1993, we surgically treated 42 patients with Wolff-Parkinson-White syndrome and Ebstein's anomaly. The patient's ages ranged from 5 months to 59 years (mean 35.3 +/- 14.0 years). There were a total of 52 accessory pathways, 48 of which were located in the right (65%) or posteroseptal (29%) area. A left-sided accessory pathway was seen in only two patients (3.8%). Division of all right-sided accessory pathways was done during normothermic cardiopulmonary bypass with the heart beating; cryocoagulation was applied together with scalpel dissection of the atrioventricular groove. Division of the left-sided accessory pathways was done with the use cold potassium cardioplegic arrest. Thirty-five of these patients underwent tricuspid valve operation for Ebstein's anomaly and 11 of them underwent tricuspid valve replacement with a bioprosthesis. All 52 accessory pathways were successfully divided, although two patients required reoperation because of tachycardia caused by accessory pathways in different positions. Three hospital deaths (7.1%) occurred. There were no late deaths during the follow-up period (mean 94.3 +/- 52.4 months), but two patients required repeat tricuspid operation because of progression of the tricuspid regurgitation. Because no repeat operations were required during long-term follow-up patients who underwent valve repair or valve replacement, correction should be indicated in some patients.