The goal of the study was to assess the safety of transesophageal-guided electrical cardioversion (ECV) with visualization of both atrial appendages after four weeks of anticoagulant therapy. 133 consecutive patients with non-valvular persistent atrial fibrillation (AF) undergoing transesophageal echocardiography (TEE) before ECV were included into the study. TEE was performed in all patients after 4 weeks of effective anticoagulant therapy. Both left and right atrial appendages thrombi were present in 63 (47.4 %) patients, left atrial appendage thrombi – in 40 (37.6 %) patients right atrial appendage thrombi – in 10 (7.5 %) patients; 20 (15 %) patients were without thrombi. In 58 (51.3 %) patients thrombi were organized, in 55 (48.7 %) patients thrombi were nonorganized. ECV was performed in patients with organized thrombi and in patients without thrombi. Procedure was delayed in patients with non-organized thrombi in atrial appendages until thrombus organization detected by TEE. Duration of anticoagulant therapy was 8 weeks in 43 (32.3 %), 12 weeks in 9 (6.8 %), 16 weeks in 2 (1.5 %) and 20 weeks in one (0.8 %) patient. There were no cases of ECV-related thromboembolism. In conclusion, TOE with both atrial appendages visualization should be performed in all patients with non-valvular AF undergoing ECV after four weeks of anticoagulant therapy. ECV with organized atrial appendage thrombi detected on TOE is a relatively safe procedure.