Introduction: We sometimes need to do DC cardioversion of organized AT and AFL, when they can not be terminated by both antral ablation, roof or inferior line, and mitral valve isthmus line ablation. In those cases, we try DC cardioversion then make right side carvotricuspid isthmus(CTI) block and try reinduction by rapid atrial pacing (RAP). But we don't know non-inducibility can be the prognostic factor of recurrence of AT, AFL or AF. Subjects and Methods : Total 48 patient who got DC cardioversion for organized AT or AFL were enrolled. We divided them into two groups. In group 1 no AFL or AT was induced and in group 2 repeated AFL or AT were induced by RAP. After 4-6 months follow up, we compared the recurrence rate of AT, AFL or AF between two groups. The induction protocol was RAP from 250ms to 200ms interval for 2 min under 5ug/min isoproterenol. We excluded reinduced AF patients, because all of them were permanent AF patients. Results: The mean age was 57.9짹10.2 years, and male was (65.9%). The number of group 1 was 31 patients (65%) and group 2 was 17 patients (35%). The recurrence rate of AT,AFL, or AF in group 1 and group 2 showed significant different recurrence rate ( 19.3% vs 52.9% p <0.003 ) between two groups. The morphologic characteristics of recurrence group were short A-A interval ( 210ms<), intermittent changing electrical sequence, not terminated by overdriving pacing, intermitent irregular A-A interval. Conclusion : Non-inducibility after DC cardioversion of organized AT and AFL after AF ablation can be good prognostic factor for recurrence of AFL, AT or AF.