BACKGROUND: Atrioventricular reentry is the most common cause of supraventricular tachycardia in Korea. Radiofrequency catheter ablation(RFCA) is now accepted to be the safe and effective treatment modality for the elimination ofr accessory pathway conduction in patient with atrioventricualr reentrant tachycardia(AVRT). METHODS: To evaluate the clinical usefulness of RFCA for the treatment of AVRT, this study was conducted in 109 patients(male 68, female 41) with atrioventricular accessory pathway and documented AVRT after electrophysiologic study. RESULTS: A total of 112 accessory pathways were identified in 109 patients. The mean power outputs of the successful ablations at the atrial side of the annulus were higher than those at the ventricular side(34.0+/-8.9W versus 20.0+/-7.6W, p<0.01), but the maximum temperatures were lower at the atrial side of the annulus than those at the ventricular side (66.4+/-14.0degrees C versus 77.2+/-6.4degrees C, p<0.01). Accessory pathway conduction was eliminated in 102 of 112 pathways successfully(success rate 91v). There were 4 nonfatal complications(3.7%). 3 patients with hemopericardium and 1 with femoral artery thrombus, during or after ablation porcedures. Recurrences of AV reentrant tachycardia or delta wave on the electrocardiogram occured in 5 patients, and 4 of them had successful second procedures. There were no late complications during a mean follow-up period of 13+/-5 months. CONCLUSION: RFCA is highly effective and safe treatment modality in ablation accessory pathway conduction.