The occurrence of late and very late thrombotic complications in association with drug-eluting stents (DES) has recently garnered much attention, but these complications are also associated with bare-metal stents (BMS). Predisposing factors for BMS thrombosis, both early and late, include noncompliance with antiplatelet agents, an exercise-induced procoagulant state, brachytherapy, small stent size, underdeployment of the stent, depressed left ventricular ejection fraction, and impaired response to antiplatelet therapy. Independent predictors of DES thrombosis include premature interruption of antiplatelet therapy, primary stenting in acute myocardial infarction, total stent length, and renal failure. Prevention depends on applying an optimal stent deployment technique at the time of the index percutaneous coronary intervention (PCI), compliance with dual antiplatelet therapy, and extending antiplatelet therapy beyond current package insert recommendations. In patients who develop late stent thrombosis, efforts to achieve rapid normalization of coronary blood flow with PCI are mandatory.