Background: The left atrial(LA) and left atrial appendage(LAA) dysfunction are important factors for thromboembolism in the patients with atrial fibrillation (AF). CHADS2 score has been revised as CHA2DS2-VASc score for better thromboembolic risk stratification in patients with AF. The aim of this study was compare both clinical schemes in predicting thromembolic risk by comparing clinical thromboembolic risk scores and echocardiographic parameters in patients with AF Methods: 309 (F/M=50/259, mean age=55짹10.4) patients with non-valvular AF who had trans-thoracic echocardiography (TTE) and trans-esophageal echocardiography (TEE) were enrolled. CHADS2 and CHA2DS2-VASc scores were calculated in each patient and correlated to echocardiographic findings. Measured TTE and TEE findings are LA volume, LA emptying fraction (EF), LAA emptying velocity, LAA EF, the presence of dense SEC and presence of left ventricular hypertrophy (LVH) (defined as >130 g/m2 in men, >110 g/m2 in women). Results: In study population, increased LAV (LAVI ���35ml/m2) was founded in 104 patients, impaired LAEF (���30 %) in 48 patients , decreased LAA emptying velocity (���20 cm/s) in 29 patients, decreased LAA EF (���30%) in 108 patients, SEC in 74 patients. Higher than 2 CHADS2 and CHA2D-Vas score was related with increased LAV, low LAEF, the presence of LVH (Table 1). But low LAA EF and low LAA emptying velocity was related with higher than 2 CHADS2-vasc score only (Table 2). There was no significant relation with the presence of SEC with the clinical score level. But combining the LAVI and LAEF with CHADS2 and CHA2DS2-VASc score showed improved predictive power in detecting SEC in LA (Table 2). Conclusion: Higher CHADS2 and CHA2DS2-VASc scores were correlated with echocardiographic markers of LA dysfunction. But only higher than 2 CHADS2-vasc score was associated with diminished LAA function. LA function measured by TTE added to the CHADS2 or the CHA2DS2-VASc scores may improve the ability predicting the presence of SEC.