For thrombus formation, three important factors, blood flow, blood component and blood vessels, have been recognized as Virchow's triad. In cardiogenic embolism with atrial fibrillation, stagnation of blood in the left atrium causes fibrin-rich thrombus. Anticoagulation is the only effective drug for prevention of this type of thrombus. In atherothrombotic and lacunar infarction, injury of endothelium and arterial vessels and platelet play a crucial role of formation of platelet-rich thrombus. Antiplatelet drugs such as aspirin, clopidogrel and cilostazole are effective for prevention of arterial thrombus and stroke recurrence, but other drugs such as statin for plaque stabilization and improvement of endothelial function could be used to reduce the recurrence of ischemic stroke.