Stent thrombosis (ST) is an uncommon but potentially lethal complication of coronary endoprothesis. Clinical trials have not shown differences in the incidence of early and late thrombosis among bare-metal stents and drug-eluting stents. Very late stent thrombosis occurs more than a year after stent implantation and is more specific of drug-eluting stents. Factors related to the patient, the stent, the coronary lesion and the technique are involved in the pathogenesis of ST. The main risk factor ST is the premature discontinuation of antiplatelet therapy. Currently, patients must receive aspirin and a thienopyridine for at least one month after the implantation of a bare-metal stent and 12 months after the implantation of a drug-eluting stent, then maintaining one antiplatelet agent indefinitely.