Background and Objective: Atrial fibrillation (AF) induced progressive left atrial (LA) enlargement. Low left atrial appendage velocity (LAAV) among patients with AF known as a higher risk of thromboembolic events. We assessed the association between LA volume and LAAV in patients with AF. Methods: Forty-three patients (mean 65 years old, 23 men) with AF underwent transthoracic echocardiography (TTE) and transesphageal echocardiography (TEE). LA volume was measured using biplane area-length method by TTE, and LAAV was measured using peak emptying velocity by TEE. Results: LAAV was significantly correlated to LA volume (r=-0.430, P<0.001) and index of LA volume (r=-0.394, P=0.019) except LA size (r=-0.266, P=0.084). Patients with LAAV <20 cm/s had an increased LA size, LA volume, index of LA volume, and intima-media thickness (IMT) of thoracic aorta. Patients with LAAV <20 cm/s had also more prevalence of spontaneous echo contrast (SEC) in LA and LAA by TEE. (Table) Conclusion: This study demonstrated that LAAV is assocated with LA volume, both of which is known to be increased cardiovascular and cerebral events.