Background: Rate control and rhythm control was recommended strategy for patients with atrial fibrillation(AF). Cardioversion, pharmacologic agent and catheter ablation was done to achieve sinus rhythm. Cardioversion and pharmacological conversion are appropriate option. We evaluate predictive factor for success of atrial fibrillation after DC cardioversion Methods: 137 patients with chronic AF to undergo cardioversion reveived serial monophasic (100, 200, 300 up to 360J)shock or serial biphasic(100, 150, up to 200J) shock. Results: 105 of 137 patients was restoration to sinus rhythm. Restoration group used more beta-blocker (29.8 vs 6.3%) and more amiodarone(32.7 vs 12.5). And enlarged left atrial dimension(4.70 vs 4.48 mm), more elderly(58.7 vs 53.9), higher body mass index(BMI, 25.3 vs 23.8) was associated to sinus conversion. Age(p=0.01), BMI (p=0.03), beta-blocker(p=0.009) were independently associated with outcome by multivariate analysis. Conclusion: DC conversion to sinus rhythm for patients with AF is associated with more elderly, higher BMI and used beta-blocker patients.