Coronary artery diseases continue to be the most common causes of mortality and morbidity in the industrialized world, especially in the setting of acute myocardial infarction. Platelets play a crucial role in thrombosis and haemostasis, which can be either beneficial or deleterious, depending on the circumstances. Platelet hyperreactivity is a multifactor process depending on genetic polymorphism, pathological state and lifestyle; it contributes to the activation of the thrombotic cascade. Under pathophysiological conditions platelets activation plays a critical role in arterial thrombosis including platelets aggregation, the basis of destabilization of coronary plaque. Despite the benefits observed in outcome when primary angioplasty is compared with thrombolysis for the treatment of acute myocardial infarction there is still some room for improvement; unfortunately the restoration of an "optimal" epicardial flow is not always related to an "optimal" myocardial reperfusion. In the recent, past several studies have shown significant benefits with the administration of glycoprotein IIb/IIIa inhibitors. Thus, the aim of the present review is to perform an update on factors associated with platelets hyperactivity and on adjunctive glycoprotein IIb - IIIa inhibitors in primary angioplasty.