BACKGROUND: Bleeding is a common and costly complication of percutaneous coronary intervention (PCI). Little is known about the risk factors for bleeding complications. OBJECTIVE: To report our PCI-related observations from a single institution and use the information to establish risk factors for short-term bleeding complications, with special focus on examining the importance of renal function. METHODS: A retrospective record review was conducted of the admission of 300 patients grouped according to antithrombotic regimen: unfractionated heparin alone (n = 187), bivalirudin (n = 26), and glycoprotein llb/llla antagonist plus heparin (n = 103). Bleeding and ischemic outcomes were tracked. A model was constructed to predict independent bleeding risk factors. RESULTS: Treatment groups differed significantly regarding any bleeding (p = 0.001), minor bleeding (p < 0.001), and length of stay (p = 0.01). Multivariate predictors of any bleeding included antithrombotic regimen, creatinine clearance (Cl-er) <30 mL/min, and hypertension. Any bleeding was associated with prolonged length of stay. Major bleeding was predicted by Cl-cr <30 mL/min and was associated with prolonged length of stay and death. Minor bleeding was predicted only by choice of antithrombotic regimen. CONCLUSIONS: The major influences on bleeding risk appeared to be Cl-er <30 mL/min and choice of antithrombotic regimen. It is important to note that other markers of renal function, including serum creatinine value and serum creatinine at a cutoff level of 1.5 mg/dL, did not predict bleeding events.