PURPOSE: Although the data of radiofrequency catheter ablation (RFCA) of supraventricular tachycardia in adults has been accumulated in several centers in Korea, few data are available on its efficacy and safety in pediatric ages. We reviewed the data in young patients who underwent this procedure in a pediatric cardiology center, to evaluate the indications, early results, complications, and short-term follow-up data. METHODS: We retrospectively reviewed the medical records and RFCA procedure reports of 17 children who underwent this procedure in pediatric cardiology center, Asan Medical Center, Seoul, Korea from January 1992 to July 1996. The mean follow-up periods was 17.8 months. RESULTS: 1) The median age of the patients was 12.3 years and all of them except two patients had structurally normal hearts. The indications of RFCA were preoperative open heart surgery in a patient, drug refractory tachycardia in 4 patients and patient's choice in other 12 patients. 2) The mechanisms of supraventricular tachycardia were 9 atrioventricular reentrant tachycardia, 6 atrioventricular nodal reentrant tachycardia (AVNRT), 1 atrial flutter and 1 atrial ectopic tachycardia (AET). Among accessory pathways, preexcitation was in 6 patients and accessory pathway located in the right side in 7 patients. In all patient with AVNRT except one, slow pathway was ablated. In the case of AET, ectopic focus located in the left atrium near the orifice of right lower pulmonary vein. 3) 16 of 18 procedures (88.9%) were successful and in 2 occasions with right sided accessory pathway and AET, the procedure failed. Ectopic focus was successfully ablated at the second attempt. The mean total procedure time was 2.7 hours (n=16) and the mean fluoroscopic time was 45.3 minutes (n=12). The average number of RF application was 11 times. There was no significant complications related with procedures. 4) There were 5 recurrences (29.4%), in 2 patients with accessory pathway and 2 patients with AVNRT. Most recurrences occured in 6 weeks after procedure. CONCLUSIONS: RFCA is a good alternative for the treatment of supraventricular tachycardia also in young patients as in adults. Early results of RFCA shows resonably good success rate but somewhat higher rate of recurrence in our center. We expect the results of RFCA in children will be improved in near future after some period of learning curve.