Coronary thrombosis plays a central role in the development, progression, and complications of atherosclerotic heart disease. As a result, pharmacologic manipulation of the hemostatic system has been the mainstay of treatment for coronary artery disease. Since platelets are the most important cellular element in the development of arterial thrombosis, many of the most effective therapies have involved the use of various antiplatelet agents. This article focuses on clopidogrel, an antiplatelet agent belonging to the class of drugs known as the thienopyridines, in the treatment of patients with coronary artery disease.