Several clinical trials have shown that antagonists of the glycoprotein IIb/IIIa receptor decreased the incidence of death, nonfatal myocardial infarction, and the need for urgent revascularization when administered immediately before or during the 24- to 48-hour period after percutaneous coronary intervention (PCI). However, these agents increased the risk of thrombocytopenia and periprocedural bleeding complications. Therefore, the relation between periprocedural bleeding complications during PCI and long-term outcome was assessed in 6,995 patients in the EXCITE trial. Periprocedural bleeding was classified as none, mild, moderate, and severe. Measured outcomes included the incidence of all-cause mortality or the composite end point (cardiovascular disease) of death, myocardial infarction, or stroke. Subjects were followed up for a median of 210 days (7 months). Mean patient age was 59.1 years, and 21.8% were women. Periprocedural bleeding complications occurred in 1,869 patients (26.7%), and blood transfusion was administered to 189 patients (2.7%). In multivariate analysis, periprocedural bleeding complications were significantly associated with increased risk of the composite outcome for mild (hazard ratio [HR] 0.80, 95% confidence interval [CI] 0.64 to 0.97), moderate (HR 2.38, 95% CI 1.78 to 3.20), and severe bleeding complications (HR 3.55, 95% CI 2.20 to 5.73) during follow-up. Also, the necessity of blood transfusion was an important predictor of the composite end point (HR 2.61, 95% CI 1.96 to 3.60). Patients in the United States were more likely to be administered a blood transfusion than non-US patients independently of cardiovascular risk factors. In conclusion, moderate and severe periprocedural bleeding complications increased the risk of mortality and incident cardiovascular events after PCI.