Background: High-density lipoprotein-cholesterol (HDL-C) is a continuous inverse cardiovascular risk factor. However, little is known about the influence of HDL-C on outcome of patients with acute coronary syndrome (ACS) undergoing percutaneous coronary intervention (PCI). Methods: From 2003 to 2009, 2169 consecutive patients with ACS underwent elective PCI were enrolled. We evaluated the impact of HDL-C on 1-year occurrence of death, non-fatal myocardial infarction and target lesion revascularization. The patients were divided into 2 groups: high HDL-C (> 50 mg/dL for female and > 40 mg/dl for male) and low HDL-C (��� 50 mg/dL for female and ��� 40 mg/dl for male). Results: patients with high HDL-C had a higher incidence of male and hypercholesterolemia. After correction for baseline differences, patients with high HDL-C had a significant lower 1-year outcome (OR 0.567, 95% CI 0.402-0.799, p=0.001). Conclusion: Independent of low-density lipoprotein-cholesterol, HDL-C was associated with better 1-year outcome in patients with ACS underwent elective PCI.