Backgrounds: HMG-CoA reductase inhibitor (statin) reduces mortality and adverse cardiac events in patients with acute coronary syndrome. We thought early statin therapy would be effective in reducing major adverse cardiac events (MACEs) in patients with acute myocardial infarction (MI). Methods: 1,159 acute MI patients who admitted and followed-up for one-year were analyzed. They were grouped by initiated time of statin after admission (Group I: < 24 hrs, II: 24 to 48 hrs, III: > 48 hrs). By sub-group analysis, 699 patients with low density lipoprotein (LDL)-cholesterol level less than 130 mg/dL were evaluated. Results: Group I had higher history of ischemic heart diseases than other groups (15.3% vs. 11.3% vs. 9.8%, p = 0.023). Other history of cardiovascular diseases and non-cardiac co-morbidities were not different in each group. Acute ST-elevation MI (STEMI) was more diagnosed in group I (69.5 % vs. 67.0 % vs. 59.3 %, p = 0.012). In coronary angiographic findings, complex lesions (type B2/C on ACC/AHA classifications) were more presented in group III (68.7 % vs. 73.4 % vs. 77.3 %, p = 0.018). No differences in involved vessel number and rate of percutaneous coronary intervention (PCI) were noted. No differences were observed in complication and in-hospital death rates among the groups (p = 0.088, p = 0.429 respectively). In one-year follow-up, MACEs and death rates have no differences in each groups (18.1 % vs. 17.5 % vs. 24.6 %, p = 0.094, 7.0 % vs. 6.6 % vs. 7.1 %, p = 0.962). In sub-group analysis of patients with LDL less than 130 mg/dL, complication rates were higher in group III (12.0 % vs. 12.0 % vs. 22.2 %, p = 0.021). There were no differences of MACE and death rate in each group at one-year follow-up (19.3 % vs. 18.7 % vs. 28.9 %, p = 0.077, 7.3 % vs. 5.7 % vs. 9. 6 %, p = 0.632). Based on prescribed time within 48 hours, MACEs at one-year follow-up was lesser than patients prescribed after 48 hours (17.8 % vs. 24.6 %, p = 0.026) Conclusion: The early statin therapy within 48 hours after admission reduced MACEs at one-year follow-up regardless of the kinds of statin and the presence of ST-segment elevation.