The authors report their experience in endocavitary radio-frequency ablation of 37 secondary pathways carried out in 33 consecutive patients. The indications for radical treatment were based solely on clinical arguments in 15 patients, on a combination of disabling signs and threatening electrophysiological signs in 17 patients and on high retrograde permeability in 1 asymptomatic patient. Endocavitary exploration revealed 26 left lateral sites, 7 posterior paraseptal sites and 4 right lateral sites. The procedure was successful in 88% of cases. Electrophysiological follow-up, carried out routinely in all the patients 2 months after the procedure, revealed a single recurrence (3%) which was treated by radio-frequency again, this time with a successful outcome. There was only one complication, a complete AVBBB following ablation of a left posterior paraseptal Kent's bundle, which required a permanent pacemaker. These results were similar to those reported in the literature and clearly demonstrate the efficacy of radio-frequency treatment of the secondary pathways, with a moderate risk of complication. These results were similar to those reported in the literature and clearly demonstrate the efficacy of radio-frequency treatment of the secondary pathways, with a moderate risk of complication. Recent advances in the field of endocavitary ablation have made it possible to change the method of handling symptomatic Wolff-Parkinson White syndromes, by enlarging the indications for radical treatment in order to enhance the comfort and quality of life of the patient.