Catheter ablation of accessory atrioventricular pathways using radiofrequency current was attempted in 61 children and young adolescents less than 18 years of age who were referred for treatment of symptomatic supraventricular tachycardia. Thirty-three children had the Wolff-Parkinson-White syndrome and 30 tachyarrhythmias related to an accessory pathway conducting only in retrograde fashion. Ablation of left sided accessory pathways was usually attempted utilizing an arterial approach to the annulus of the mitral valve, only in one case we used the transseptal approach, while the venous route to the atrial aspect of the tricuspid valvular annulus was chosen for right sided accessory connections. Ablation of 55 of 63 accessory connections was achieved (87% success) with a range of 1 to 42 applications of radiofrequency current. The sessions were completed within 19 to 180 minutes, and we used within 16 to 45 watts of radiofrequency current. Two patients had complications as a result of their ablation procedure. One patient had complete heart block but did not require pacemaker implantation, and other one had mitral regurgitation. A second session was necessary in three patients, two of three accessory pathways were ablated, giving a success rate of 90%. During a one year period of follow-up, we had 4 recurrences (7.2%). Catheter ablation using radiofrequency current is a highly effective and safe curative approach for treating young patients with supraventricular tachycardia mediated by accessory pathways.