OBJECTIVE PJRT occurs predominantly in infants and children and is limited to small series in adults. The aim of this study was to describe the clinical presentation, electrophysiological characteristics, feasibility and safety of radiofrequency ablation, and the long-term prognosis in a large group of adult patients with the permanent form of junctional reciprocating tachycardia (PJRT). RESULTS Forty-nine adult patients (22 male and 27 female; mean age 43+/-16) with a diagnosis of PJRT confirmed at electrophysiological study were included. Eight patients (16%) presented with tachycardia-induced cardiomyopathy (TIC). Ventricular rate was 146+/-30 bpm. The arrhythmia was permanent or incessant in 23/49 cases (47%) and paroxysmal in 26/49 (53%). A significant correlation was found between symptom duration and tachycardia rate (r(2)=0.12, P=0.01). The accessory pathway (AP) was located in the right posteroseptal region in 37 cases (76%) and in atypical sites in 12 cases (24%). Patients with the incessant or permanent form of PJRT had longer duration of symptoms, more frequently TIC and a slower tachycardia rate. Radiofrequency catheter ablation was initially successful in 46 cases (94%) without any serious complication. Long-term success rate was 100% (49/49 patients) in the absence of any antiarrhythmic drug treatment (mean follow-up 49+/-38 months). Regression of TIC was observed in all cases (8/8). CONCLUSIONS PJRT in adults is often paroxysmal (53%), and the retrograde slowly conducting, decremental AP is not infrequently in a non-posteroseptal location. Radiofrequency catheter ablation is highly effective and should be considered as the treatment of first choice in adult patients with PJRT.