Introduction: Termination of atrial fibrillation (AF) is acceptable end point of stepwise approach of catheter ablation (CA) for substrate-dominant persistent AF (PeAF). However, termination can be observed even before achieving complete pulmonary vein isolation (PVI) in some patients. The objectives of this study are to evaluate the clinical characteristics and clinical outcome of PeAF patients in whom AF was terminated before completion of PVI. Methods: Among 164 patients with PeAF who underwent CA since 2006, termination of AF before completion of PVI was observed in 16 patients (group I). AF was re-induced and ablation continued until induced AF terminated. 68 patients who underwent PVI and multiple linear ablations until initial AF terminated (group II) were compared. Results: There were no differences in the follow-up period, sex, age, CHADS2 score, LA size and LV ejection fraction between 2 groups. There was also no difference in post-ablation medications including antiarrhythmic drug or beta-blocker between 2 groups. The patients who terminated AF during PVI (group 1) required shorter ablation (106.4짹35.8 min vs. 167.3짹47.5 min, p<0.01) and procedure time (243.5짹61.1 min vs. 317.5짹92.7, p=0.01). The total number of multiple linear ablation was significantly smaller in group I than those in group II (p<0.05). The early recurrence rate of AF or atrial tachycardia (AT) during and after blanking period were slightly lower in the group I than group II (25.0% vs. 51.5%, p=0.121, 16.7% vs. 42.6%, p=0.115), respectively. Conclusions: The patients who terminated persistent AF with minimal ablation tended to have lower early and late recurrence rate even with less extensive ablation. These findings support that minimal proarrhythmic substrate and/or continuously triggering focus underlie the mechanism of PeAF in some patients.