The left atrial appendage (LAA) is a blind pouch derived from the primordial LA, which is formed mainly by the adsorption of the primordial pulmonary veins and their branches. The main left atrium (LA) cavity which is a smooth walled structure develops later from the outgrowth of the pulmonary veins. Blood supply to the LAA is derived from the right coronary artery (RCA) and left coronary artery (LCA) artery at the atrioventricular groove. Left atrial appendage has physiological characteristics distinct from the LA. It is not a static structure, but is highly mobile, distensible and dynamic. Pattern of LAA contraction is different from rest of the LA. This chapter covers the echocardiographic imaging of LAA and echocardiographic-guided LAA closure. Systemic anticoagulation is the primary means of preventing thromboembolism in patients with AF.