Red cell distribution width (RDW), a measure of the variability in size of circulating erythrocytes, is an independent predictor of mortality in patients with cardiovascular disease. We hypothesized that RDW is a prognostic marker of death, myocardial infarction and unplanned revascularization in a broad population undergoing percutaneous coronary intervention (PCI). We investigated the prognostic value of RDW derived from a complete blood count drawn ≤24 h of PCI in 1,689 patients at four centers who underwent PCI between 2004 and 2007 in the evaluation of drug eluting stents and ischemic events registry. Patients who underwent blood transfusions were excluded. Multivariable analyses of death, MI, unplanned revascularization, and the combined occurrence of these events at 1 year were performed using methods from survival analysis. The analysis was adjusted for creatinine ≥1.5 mg/dL, hemoglobin, congestive heart failure, coronary artery bypass grafting history, male sex, BMI, atherosclerosis of ≥2 coronary vessels, and hypertension. In univariate analysis of RDW stratified by quartiles, membership in the highest quartile was a predictor of mortality as compared to the lowest quartile (HR 5.07, CI 2.07-12.40, p < 0.001). In multivariate analysis, RDW was not an independent predictor of unplanned revascularization after PCI; however, RDW remained an independent correlate of 1 year mortality (HR 1.65, CI 1.22-2.23, p = 0.001); with a continuous net reclassification improvement of 46.5% (95% CI 15.1-76.4%) and a relative integrated discrimination improvement of 57.8% (95% CI 22.1-94.9%) after PCI. RDW is a widely available independent correlate of 1-year mortality after PCI that increases the discriminative value of risk prediction in these patients.