Objective: The aim of this study was to investigate the influence of red blood cell distribution width (RDW) on the long-term prognosis of percutaneous coronary intervention (PCI) for patients with non-ST-segment elevation acute coronary syndrome (NSTEACS). Methods: Two thousand one hundred and eighty-five NSTEACS cases with coronary artery disease and preoperative record of RDW who under went elective PCI treatment from July 2009 to September 2011 were selected. According to preoperative RDW levels, the patients were divided into two groups. One thousand one hundred and seventy cases belonged to the RDW < 12.2 group, 1015 cases belonged to RDW >= 12.2 group. The clinical characteristics and the incidence of postoperative mortality in the two groups were compared. There was a follow-up period of 540 days. Results: Patients in the RDW >= 12.2 group were females with characteristics such as: hypertension, history of cerebrovascular disease, hospital use of beta-blockers and high body mass index (BMI) at admission, low haemoglobin and total cholesterol levels. The postoperative mortality of RDW >= 12.2 group (2.7% vs 1.0%, p = 0.004) was significantly higher than that of RDW < 12.2 group. In multivariate Cox regression analysis, after adjustment for other factors, RDW >= 12.2 in the patients with postoperative PCI was an independent predictive factor for mortality (HR 2.171, 95% CI 1.007, 4.680, p = 0.048). Conclusion: High RDW in patients with postoperative PCI was an independent predictive factor for mortality.