Background : Beyond lowering lipids, statins have favorable effects on platelet adhesion, thrombosis, endothelial function, plaque stability and inflammation. The vascular injury from percutaneous coronary intervention (PCI) induces platelet activation, thrombosis and inflammation within the vessel wall. The aim of this study was to determine the effects of statin therapy in acute myocardial infarction (AMI) patients who underwent PCI. Methods : A total of 254 patients with AMI who underwent PCI between June 2001 and June 2002 at Chonnam National University Hospital were divided into two groups: Group I (n=134, 60.1짹12.7 years, male 85.1%) who were treated with simvastatin and Group II (n=120, 58.9짹9.4 years, male 83.3) who were not treated with simvastatin after PCI. Results : The levels of total cholesterol, triglyceride and low density lipoprotein-cholesterol were more decreased and the level of high density lipoprotein-cholesterol was more increased in Group I than in Group II. The levels of C-reactive protein (CRP), white blood cell and monocyte count and fibrinogen were more decreased in Group I than in Group II. There was no significant difference in major adverse cardiac event during hospitalization, but statin therapy was associated with a significant reduction in restenosis rate (19.1% vs 32.6%, p=0.036) and repeat revascularization rate (17.0% vs 30.4%, p=0.031) during one-year clinical follow-up after PCI. The MACE-free survival rate was higher in Group I than in Group II (81.7% vs 62.3%, p=0.001). The independent predictors for MACE at one year after PCI were CRP above 0.5 mg/dL, left ventricular ejection fraction less than 40%, old age above 75 years, lesion type B2/C according to the American College of Cardiology/American Heart Association classification and statin use (p<0.001, =0.001, 0.002, 0.023, 0.040, respectively). Conclusion : Statin therapy after PCI is associated with a reduction in the incidence of restenosis, repeat revascularization and high MACE-free survival during one-year clinical follow-up after PCI in AMI.