Objective: To study the electrophysiologic characteristics and the radiofrequency catheter ablation (RFCA) efficacy of permanent junctional re ciprocating tachycardia(PJRT). Methods: Seven patients (3 men , 4 women) with diagnosis of PJRT were confirmed at electrophysiologic study. Radiofrequency energy was applied at the site of atrioventricular annulus with the earliest retrograde atrial activation during tachycardia or right ventricular pacing. The accessory pathway was ablated to block its conduction using routine RFCA method. Results: All patients had typical attacks of sup raventricular tachycardia with normal heart function, some of them were incessant. During tachycardia long R-P′ intervals, (196±24) ms, were found, and R-P ′/ P′-R ratios were mostly greater than 1 with retrograde Pwaves negative in the inferior leads. Electrophysiologic studies demonstrated all patients with concealed slow conducting accessory pathway for retrograde conduction. At the abl ation sites V-A intervals were (163±22) ms, and decremental conducting properties could be found. Seven accessory pathways were located in right posteroseptal in 4 patients, right midseptal in 1, left posteroseptal in 1 and left posterior in 1. All ablations were successful at the first operation with a mean of (11± 3) min of X-ray time, and without adverse effects. During the follow-up, all patients remained free from tachycardia. Conclusion: PJRT is a special type of atrioventricular reentry tachycardia through concealed slow and decremental conducting accessory pathway. Catheter ablation is an effective and safe curative treatment.