Background : Atrioventricular nodal reentry tachycardia (AVNRT) is the most common regular supraventricular tachycardia in both general population and elderly patients. The aim of this study was to investigate safety and efficacy of radiofrequency catheter ablation (RFCA) of atrioventricular nodal reentry tachycardia (AVNRT) in the elderly. Methods: This study included consecutive 273 symptomatic AVNRT patients who underwent RFCA for slow-pathway in our institution. The 272 patients who underwent successful RFCA were divided into two groups: group I patients younger than 65 years (n = 226, 44.6짹12.9 years, male:female=88:138) and group II patients more than 65 years (n=46, 69.0짹3.6, male:female=9:37). We compared baseline clinical, electrocardiographic, electrophysiologic characteristics and complication of RFCA between two groups. Results: In group II patients, female and coronary artery disease were more common (p<0.05). But, there was no difference in left ventricular ejection fraction. Preexisting prolonged PR interval (>200 ms) appeared more common in group II (group I vs. group II = 4 (1.8%):3 (6.5%), p=NS). PR interval, cycle length of baseline sinus rhythm and tachycardia were longer in group II (group I vs. group II = 151.0짹20.3 vs. 162.1짹21.4, 799.3짹146.2 vs. 864.3짹159.8, 351.3짹53.4 vs. 384.9짹57.0, p<0.05, respectively). There was no difference in complications including AV block associated with RFCA. Second degree or complete AV block developed in 12 patients (group I vs. group II = 9(4.0%):3(6.5%), p>0.05) transiently except 2 group II patients, of whom only one patient required a permanent pacemaker implantation. AVNRT recurred in 5 patients (2.2%) only from group I. Conclusion: RFCA in elderly patients is also safe and effective as in younger patients. Therefore, RFCA of AVNRT should be considered also in the elderly patient.