Background: The efficacy of inhibition of renin-angiotensin-aldosterone system in patients with acute myocardial infarction (AMI) has been established, and the prescription of angiotensin converting enzyme inhibitor (ACEI) is recommended as class I indication for all AMI patients, whereas that of angiotensin II receptor blocker (ARB) as class IIa. This analysis from the Korea Acute Myocardial Infarction Registry (KAMIR) assessed the beneficial effect of ARB, ACEI, and combination of both drugs for long term clinical outcomes in patients with AMI. Method: 5627 AMI patients (63.8 짹 12.7 years, 3825 males) who were followed-up during one year after discharge were divided into four groups; ARB alone group (n=481, 63.4짹13.1 years, 318 males), ACEI alone group (n=3657, 63.1짹12.6 years, 2570 males), combination group (n=270, 66.2짹11.9 years, 179 males), and control group (no ACE inhibitor or ARB) (n=1219, 65.7짹12.6 years, 758 males). We retrospectively evaluated major adverse cardiac events (MACE), including cardiac death, reinfarction, coronary artery bypass graft, heart failure, and target lesion revascularization during one-year clinical follow up. Result: The baseline clinical characteristics were similar among 4 groups including clinical impression, hemodynamic parameters, Killip class, risk factors, electrocardiographic, echocardiographic, and coronary angiographic findings. At 1-year clinical follow up, there was no significant difference in the rate of MACE between ARB alone and ACEI alone groups [97 patients (20.2 %) vs. 787 patients (21.5 %), relative risk (RR)=0.92; 95% confidence interval (CI)= 0.73 to 1.17; p=0.496)]. As compared with the control group, both the ARB alone group and ACE inhibitor alone group had lower rates of MACE (20.2 % vs. 47.9 %, p<0.001, and 21.5% vs. 47.9%, p<0.001, respectively). The combination group had a higher rate of MACE (74 patients) compared with the ARB alone group (27.4% vs. 20.2%, RR=1.495; 95% CI, 1.06 to 2.12; p=0.023) and ACEI alone group (27.4% vs. 21.5%, RR=1.377; 95% CI=1.04 to 1.82; p=0.024). Conclusion: The beneficial effects of ARB were equivalent to those of ACEI in AMI and the combination of two drugs was associated with more adverse events.