Platelets have a key role in atherosclerosis, thrombosis, and acute coronary syndromes. Therapeutic manipulation of platelet function has focused principally on the use of aspirin, which has proved effective in many clinical situations, despite its relatively weak antiplatelet action. More recently, the platelet glycoprotein IIb/IIIa receptor has been identified as the pivotal mediator of platelet aggregation, making it a logical target for control of the platelet response to vascular injury. This review summarizes the current state of knowledge of the biology of glycoprotein IIb/IIIa receptors and examines the development of agents that inhibit these receptors — a diverse group of . . .