Ablation of accessory pathway (AP) of any location was performed either with a right or a left approach (patent foramen ovale, transpeptal or a retrograde transvalvular aortic catheterism in 121 patients. The best ablation site was localized: 1) by the recording of a potential likely with the Kent bundle activation; 2) the earliest site of retrograde atrial activation during orthodromic reciprocating tachycardia (80 +/- 35 ms); 3) first ventricular potentials recorded ahead or synchronous with the delta wave in standard leads; 4) disappearance of preexcitation due to the pressure of the catheter on the AP (8 patients); 5) good degree of pace-map concordance with the major preexcitation. Two 160 joules cathodic shocks in close succession induced the disappearance of preexcitation in 113 patients. No recurrence of arrhythmia occurred in 118 patients without any preventive treatment with a follow-up ranging from 2 to 49 months (10 +/- 8). No serious side effect were observed except three permanent complete AV block. However one of them occurred after an unsuccessful surgical attempt which obviously had damaged the AV junction. Fulguration is efficient in any location of AP and can be the first line treatment in patients at risk with the WPW either symptomatic or not. These results indicate that appropriate treatment of patient the Wolff-Parkinson-White syndrome could be reassessed.