Background : It is well known that catheter ablation is very effective treatment modality for atrial fibrillation(AF). However many people have developed so many treatment strategies to improve success rate. We have got good results with combination method of 3D mapping system and large sized-lasso. Materials and Methods : 154 patients performed AF ablation due to drug refractory paroxysmal, persistent and permanent AF were enrolled. 69 patients underwent segmental pulmonary vein isolation (PVI) (Group 1), 21 patients have got 3D mapping guided circumferential ablation (Group 2) and 64 patients were performed the combination method of conventional CARTO or CARTO-Merge and large-sized(30-35mm) lasso (Group 3). In combination method, both continous antral line on the CARTO map and electrical conduction block at the antrum was confirmed by lasso. We compared the recurrence rates of each groups and analyzed some factors affecting recurrence. Results : 97 patients were men and mean age was 57짹10. Recurrence rate of paroxysmal AF in Group1, 2, and 3 were 29.6%, 23.1%, and 15.1% and of persistent AF were 40.0%, 33.3%, and 22.3% . It showed significant decrease of recurrence between Group 1 and group 3 (p=0.042), but did not show between Group 2 and Group 3 (p=0.053). Neither paroxysmal nor chronic AF group did not show significant difference between the three Groups. In multiple logistic regression, large sized-lasso was the strongest predictable factor of recurrence (Odd ratio:2.18, 95% CI: 1.099-7.118) and LV ejection fraction could be predictable for recurrence (p=0.049). Conclusion : Combination method of CARTO merge and large sized-lasso might be more effective strategy than segmental PVI and conventional 3D mapping guided circumferential ablation.