All patients operated because of WPW-syndrome between 1980 and 1990 at the University clinics of Zurich were followed up by clinical examination and by electrocardiography. Relief from symptoms (tachycardia, vertigo and/or syncopes) was defined as "symptomatic" success, lack of preexcitation in the ECG at rest as "surgical" success. Overall 56 patients (40 men, 16 women) aged from 13 to 66 years had been operated in the stated time period. Before operation 52 of these patients had pre-excitations in the ECG, 54 had tachycardia and 23 had syncopes. None of the patients died from the operation. In order to localize the AAVVs epicardial cartography was performed in all patients during operation before the AAVVs were cut through an endocardial access. The follow-up was possible after an average interval of 5.5 years (1-120 months) in 50 of the 56 patients. One patient died 10 years after operation from heart failure. 6 patients were reported to be out of the country. The follow-up revealed symptomatic success of the intervention, defined as absence of tachycardia, in 88% (44 out of 50). In 84% (42 out of 50) also a surgical success of the operation was found. In these patients the accessory atrio-ventricular bundle had been successfully ablated, and they were free of tachycardia and of preexcitation in the ECG. Two patients with persisting preexcitation remained free of clinical symptoms. Insofar the rate of symptomatic success was higher than the rate of surgical success. Summarizing the results surgical transsection (ablation) of an accessory atrioventricular bundle in patients with WPW-syndrome is a good therapeutic option with favorable long term success. It has today still its place--in selected cases--as alternative to the now available radio-frequency ablation.