Radiofrequency catheter ablation of bypass tract is a treatment of choice in symptomatic patient with preexcitation. Both retrograde aortic and transseptal approach are used with similar rate of success and complication. To avoid patient discomfort and complication related to manual compression or use of closure device, radial artery is widely used in percutaneous coronary intervention. We report a case in whom ablation catheter was advanced via radial artery and successful catheter ablation was performed without complication. 37-year-old man with preexcitation was admitted to our hospital. He had recurrent paroxysmal palpitations and there was documented paroxysmal supraventricular tachycardia. 12-lead ECG showed a sinus rhythm and delta wave with negative polarity in I, and aVL and positive polarity in V1, suggesting left free-wall accessory pathway. Orthodromic atrioventricular reentrant tachycardia was reproducibly induced by single atrial extrastimulation. After confirmation of negative Allen���s test, cannulation of left radial artery was done. 7-French mapping/ablation catheter was advanced through radial artery. Mapping of mitral annulus showed earliest ventricular activation at 2 o���clock area where local ventricular activation time preceding the delta wave by 14 ms. Delivery of RF energy at the target area eliminated the delta wave within 3 seconds. RF energy was delivered for 70 seconds. There was no recurrence of preexciation 1 month after ablation. Access to left ventricle or mitral annulus via radial artery may be considered when peripheral arterial disease precludes femoral arterial puncture or there is little experience of transseptal catheterization.