Radiofrequency catheter ablation of atrioventricular accessory pathways was performed in 125 cases of the Wolff-Parkinson-White syndrome (type-A:54, type-B: 29, concealed: 42) complicated with drug-refractory and symptomatic atrioventricular reentrant tachycardia and/or paroxysmal atrial fibrillation. A total of 135 accessory pathways were identified: 50 left free-wall manifest, 34 left free-wall concealed, 21 right free-wall manifest, 2 right free-wall concealed, 15 posteroseptal manifest, 10 posteroseptal concealed, 2 right anteroseptal manifest and 1 right anteroseptal concealed. Accessory pathway conduction was successfully eliminated in 133 of these 135 accessory pathways (99%). Two right posteroseptal pathways were eventually ablated with direct current. Successful ablation required a mean 5.2 applications of radiofrequency current, a mean total energy of 2615 J and a mean fluoroscopic time of 52 min. The mean number of applications, applied energy and fluoroscopic time were greater in the right free-wall pathways than in the left free-wall pathways, and in the concealed pathways than in the manifest pathways. None of the procedures produced complications. During a mean follow-up period of 11.5 months, 1 right free-wall accessory pathway recurred and was ablated successfully in a repeat session. These results suggest that radiofrequency catheter ablation of accessory pathways is highly effective and safe irrespective of the accessory pathway location and properties, although these factors can affect the difficulty of this procedure. This technique may be an alternative to surgical therapy for Wolff-Parkinson-White syndrome with drug-refractory and symptomatic supraventricular tachyarrhythmias.