Background: Acute thrombosis after atherosclerotic plaques disruption is a major complication of primary atherosclerosis, leading to acute ischemic syndromes and atherosclerotic proression. Vitronectin (VN) is multifunctional glycoprotein in blood and in the extracellular matrix. It binds glycosaminoglycans, collagen, plasminogen and urokinase receptor. VN stabilizes the inhibitory confirmation of plasminogen activation inhibitor-1 (PAI-1). Vitronectin may control the clerance of vascular thrombi by binding and stabilizing PAI-1, a key regulator of fibrinolysis. Therefore, VN is generally regarded as a cofactor for PAI-1 activity. On the other hand vitronectin binds to platelet glycoproteins may mediate platelet adhesion and aggregation at sites of vascular injury. Previous studies showed that anti-VN antibodies inhibit platelet aggregation in vitro, suggesting that vitronectin contributes to platelet accumulation at sites of vascular injury. In this study; we investigated the levels of plasma vitronectin in patients with Coronary Artery Disease (CAD) and control group.