Radiofrequency catheter ablation (RFCA) has been established as an effective and safe treatment modality for atrioventricular nodal reentrant tachycardia and WPW syndrome. Surgical ablation or direct current catheter ablation had been performed to cure focal atrial tachycardia (AT), however, these treatments had limitations such as the need of open thoracotomy or the risk of barotrauma. RFCA could be an effective treatment modality for cure of AT. We performed RFCA for AT in 22 patients (male 13, mean age 38.1±15.4 years) among 831 patients who underwent electrophysiologic study between Jul. 1996 and May. 1999. Clinical pattern of tachycardia was paroxysmal (17 patients) or incessant (mean duration of symptoms, 41.1±42.3 months). Associated cardiac diseases were tachycardia-mediated cardiomyopathy (3 patients), aortic stenosis (1 patient) and ventricular septal defect with pulmonic stenosis (1 patient). AT was induced by programmed electrical stimulation in 17 patients: AT in the other 5 patients was incessant. The RFCA was successful in 17 patients (77.3%). The mean interval between atrial electrogram of mapping catheter and P wave of surface ECG was -53.5±24.9msec in 17 successful sites. Fractionated atrial activities were invariably found in the successful sites. Successful sites of RFCA for right AT were around coronary sinus ostium (5), crista terminalis (4), lower portion of sinus node (1), inferior portion of tricuspid annulus (1), and His area (1), respectively. In left AT, lateral portion near atrioventricular groove (2), inferoposterior portion (2) and near left atrial appendage (1) were successful site. During follow-up (mean 23 months), one patient had recurrence (recurrence rate 5.9%). RFCA for AT is an effective and curative treatment in selected cases.