Background: Transesophageal echocardiography(TEE) gui-ded cardioversion to restoration of sinus rhythm is a therapeutic option in patients with atrial fibrillation(AF). Anticoagulation at the time of and after cardioversion is necessary to prevent formation of new thrombus during atrial stunning period. We aimed to evaluate the efficacy and safety to TEE guided cardioversion with low molecular weight heparin(LMWH)in patients with atrial fibrillation. Methods: We followed up 208 patients with persistent AF(mean age: 65.5±10.2 years) who were attempted TEE guided cardioversion. LMWH were used as an anticoagulant and warfarin therapy was continued. Results: Cardioversion were performed in 183 patients. Sinus rhythm restored in 144 patients(78.7%). Mean follow up duration was 155 days. No cardiac death occurred. In the early follow up period(within 30 day) one thromboembolic event(0.54%) occurred in a patient who was cardioverted. Two patients who had not been cardioverted because of left atrial thrombus presented embolic stroke, one in early and another in late followup period. All embolic complications occurred in patients who had been taking warfarin and whose INR level was subtherapeutic at the time of stroke. Sinus rhythm was maintained in 64%and total hemorrhagic complications occurred in 4.8%of the patients in long-term follow-up. Conclusion: TEE guided cardioversion with a short-term anticoagulation protocol using low molecular weight heparin is a safe and effective method in restoring and maintaining sinus rhythm and enables us to make earlier cardioversion in atrial fibrillation. Anticoagulation at the time of and after cardioversion is necessary to prevent formation of new thrombus during atrial stunning period. We aimed to evaluate the efficacy and safety to TEE guided cardioversion with low molecular weight heparin (LMWH) in patients with atrial fibrillation. Methods: We followed up 208 patients with persistent AF (mean age: 65.5 ± 10.2 years) who were attempted TEE guided Results: Cardioversion were performed in 183 patients. Sinus rhythm restored in 144 patients (78.7%). Mean follow up duration was 155 days. No cardiac death occurred. In the early follow up period (within 30 day) one thromboembolic event (0.54%) occurred in a patient who was cardioverted. Two patients who had not been cardioverted because of left atrial thrombus presented embolic stroke, one in early and another in late followup period. All embolic complications occurred in patients who had taken taking warfarin and whose INR level was subtherapeutic at the time of stroke. Sinus rhythm was maintained in 64% and total hemorrhagic complications occurred in 4.8% of the patients in long-term follow-up. Conclusion: TEE guided cardioversion with a short-term anticoagulation protocol using low molecular weight heparin is a safe and effective method in restoring and maintaining sinus rhythm and enables us to make earlier cardioversion in atrial fibrillation.