Background: The elderly patients with acute coronary syndrome (ACS) usually have more presence of comorbidities such as diabetes mellitus, hypertension, more complex coronary artery lesions, and reduced cardiac and overall physiologic reserve, resulting higher mortality and serious complications. Statin therapy in ACS patients has been proved to improve clinical outcomes. However, little is known about the effect of statin therapy in the very elderly patients with acute myocardial infarction (AMI). Methods: We analyzed 2,096 eligible AMI patients (84.5짹3.9 years old) who were older than 80 years old and survived at discharge from Korean AMI Registry (KAMIR). They were divided to two groups according to the prescription of statin at discharge (Statin group; n=725, Non-statin group; n=1,371). The primary end point was the composite of 1-year major adverse cardiac events including death, recurrent myocardial infarction (MI), target vessel revascularization and coronary artery bypass grafting.Results: In-hospital mortality in AMI patients who were older than 80 years old was 11.6%. 1,487 (70.9%) patients underwent PCI and the success rate of percutaneous coronary intervention (PCI) was 97.8%. Clinical characteristics of both groups were similar except that statin group had more female gender and had higher serum levels of high sensitivity c-reactive protein and low density lipoprotein-cholesterol. Statin group also had more diagnosis of ST segment elevation MI. Angiographic characteristics were comparable between the groups. Statin therapy reduced the risk of the composite the primary end point (20.4% vs. 29.1%, p=0.001, adjusted hazard ratio [HR] 0.69, 95% confidence interval [CI] 0.54-0.87, p=0.002). Statin therapy reduced the risk of cardiac death (7.2% vs. 11.9%, p=0.006, adjusted HR 0.67, 95% CI 0.46-0.98, p=0.039). However, there were no differences in the risk of recurrent MI, repeated PCI, and target vessel revascularization (TVR). Statin therapy was the independent prognostic factor of 1-year MACEs as well as diabetes (HR=1.41, 95%CI: 1.09-1.83, p=0.009), and Killip class III/IV (HR=1.93, 95% CI:1.49-2.49, p<0.001). Conclusions: Although statin therapy could not reduce repeated PCI rate or TVR in the very elderly AMI patients, it had beneficial effects in the risk reduction of 1 year MACE, mainly due to the risk reduction of cardiac death