Background: Long-term treatment with lipid-lowering therapy, especially with statins, has shown benefit in patients following non-ST elevation myocardial infarction (MI) and unstable angina. There were no published data regarding statin effects in terms of cardiac death, myocardial infarction and target lesion revascularization after the DES implantation for primary percutaneous coronary intervention (PCI) in ST-elevation myocardial infarction (STEMI). Methods: These patients were analyzed to establish the effect of statin for the clinical outcomes in patients in STEMI following primary PCI. All patients belong to KOMER trial (A Korean Multicenter Endeavor Trial, a prospective, open-labeled, randomized multi-center trial at 11 centers in Korea). The primary endpoints were major adverse cardiac event (MACE; the composite of cardiac death (CD), recurrent MI and ischemia-driven target lesion revascularization (TLR)) at 12 months. Results: Total 575 patients who were completed more than one year were analyzed (statin group = 495, non-statin group = 80). One year MACE were 11.2% in statin group and 3.6 % in non-statin group (p=0.003). In univariate logistic regression, the predictors of one year MACE were age (odds ratio 1.307, 95% confidence interval [CI] 1.002-1.073), diabetes (odds ratio 2.311, 95% CI 1.023-5.220), diastolic blood pressure (DBP) (odds ratio 0.974, 95% CI 0.950-0.999) and the use of statin (odds ratio 0.324, 95% CI 0.139-0.759) but MACE was not affected by stent difference. In multivariate logistic regression, the most powerful predictor of one MACE were the use of statin (odds ratio 0.320, 95% CI 0.135-0.757). Conclusions: The use of statin improved one year MACE in patients with STEMI received primary PCI and was most powerful predictor of one year MACE.