Introduction Atrial fibrillation (AF) termination has been used as the endpoint of radiofrequency catheter ablation (RFCA) of long-lasting persistent AF (PeAF). It remains unclear whether inducibility test after termination of AF or further ablation of induced atrial tachycardia (AT) if any, has incremental benefit or not. We hypothesized that induced slow AT in this context indicates residual proarrhythmic substrate, therefore, elimination of these AT leads better outcome of RFCA of PeAF. Methods: In 155 long-lasting PeAF patients underwent RFCA (pulmonary vein isolation with ablation at the multiple atrial sites), inducibility was tested by rapid atrial pacing after achieving AF termination. Eighty patients (51.6%) showed positive inducibility of sustained ATs were analyzed. ATs were defined as organized arrhythmia with stable cycle length (CL) lasting longer than 5 minutes. Results: One hundred fifty-one ATs were induced in 80 patients. The average number of induced ATs was 1.9 짹 1.3 per patient (range 1 to 8). Of 151 ATs, ATs were terminated by RFCA in 44, spontaneously in 11, by pacing in 36 and by cardioversion (CV) in 60. A mean CL of induced ATs terminated by RFCA or spontaneously was longer than those terminated by pacing or CV[275짹67ms (range 150 to 469ms) vs. 241짹55ms (range 139 to 428ms), p<0.01). Among 80 patients, the termination mode of final induced ATs was RFCA in 20 patients, spontaneously in 4, pacing in 12 and CV in 44. During a follow-up period of 33 짹18 months, AT/AF recurred in 13% of the patients with AT terminated by RF or spontaneously, while in 23% of the patients who terminated AT by CV or pacing at the end of procedure (p>0.05). Conclusions: The CL of induced AT terminated by RFCA or spontaneously was longer than those terminated by pacing or CV. RFCA targeted induced ATs with longer CL (>270 ms) after termination of PeAF decreased recurrence of AT/AF.