Objectives. The purpose of this study was to determine the outcome of a group of closely followed-up pediatric patients who had undergone radiofrequency ablation for cardiac arrhythmias. Background. Although radiofrequency ablation in children has been shows to be effective and safe in the short term, results of longer term follow-up of these children must he considered when determining the place of radiofrequency ablation in the management of pediatric arrhythmias. Methods. One hundred children aged 2 months to 17 years underwent a total of 119 radiofrequency ablation procedures for cure of tachycardia. Follow-up clinical data, electrocardiograms and 24-h Holter monitors were obtained and analyzed. Results. All patients were alive, and none were lost to follow-up after a mean follow-up of 21.5 months (range 6 to 50). Success at last follow-up included accessory pathways in 66 (89%) of 74 patients, atrioventricular (AV) node reentry in 15 (88%) of 17, intraatrial reentry in 2 (67%) of 3, atrial flutter in 3 (100%) of 3, atrial ectopic tachycardia in 2 (67%) of 3, junctional ectopic tachycardia in 1 (100%) of 1 and ventricular tachycardia in 2 (100%) of 2 (overall success, 90 [90%] of 100). All recurrences were observed within 6 months of ablation. Major and minor complicatons (7%) included chest burn (one patient), foot microembolus (two patients), hematoma without pulse loss (four patients), femoral arteriovenous fistula requiring repair (one patient) and transient Mobitz I AV block (one patient). Immediate success, recurrence and complication rates were similar in the ≥12-year old versus the < 12-year old group. Echocardiograms, available in 109 (92%) of 119 patients, showed possible procedure-related abnormalities in 2 (mitral regurgitation in 1, tricuspid regurgitation in 1, both mild), with no aortic insufficiency after 30 left-sided ablations performed by the retrograde approach. Follow-up Holter monitors, available in 77 (77%) of 100 patients, showed possible procedurerelated abnormalities in 5 (frequent atrial ectopic tachycardia in 2, atrial flutter in 1, accelerated ventricular rhythm in 2). There were no early or late deaths. Conclusions. In children, the risks of radiofrequency ablation are low at follow-up evaluation. Longer-term follow-up of children undergoing radiofrequency ablation will be necessary to determine whether coronary abnormalities or serious new arrhythmias will develop.