Background: Studies of elderly patients have reported a lower rate of successful revascularization and more adverse outcomes in octogenarians presenting with an acute myocardial infarction (AMI). Objectives: The aim of this study was to evaluate the clinical findings and mid-term clinical outcomes in octogenarian AMI patients. Methods: Between October, 2005 and December 2006, 621 patients were admitted for AMI (439 STEMI and 182 NSTEMI). We divided the patients into two groups: octogenarians (n=59) and non-octogenarians (n=562). We compared clinical, angiographic, and procedural characteristics and we observed mortality and target lesion revascularization rates during 6-month follow-up between octogenarian AMI and non-octogenarian AMI patients. Results: Octogenarians complained of dyspnea (15% vs. 7%, p=0.023) rather than chest pain more frequently on admission, had more history of previous angina (56% vs. 41%, p=0.026), had higher Killip class on admission (Killip class III/IV: 20% vs. 11%, p<0.001), and had more atrial fibrillation (9% vs. 3%, p=0.041). Octogenarians had lower ejection fraction (53짹13% vs. 56짹12%, p=0.047), had higher hs-CRP (4.0짹4.8 mg/dl vs. 2.0짹3.0 mg/dl, p=0.004) and NT-pro BNP levels (5067짹7846 pg/ml vs. 2545짹5731 pg/ml, p=0.025) than non-octogenarians. On diagnostic coronary angiogram, octogenarians had more multivessel disease (involved vessel number: 2.1짹1.1 vs. 1.8짹1.0, p=0.032), had more ACC/AHA type C lesions (54% vs. 36%, p=0.031), and were associated with no-reflow (post-procedure TIMI flow grade 0, 1, and 2) more frequently compared with non-octogenarians (15% vs. 5%, p=0.012). During 6-month follow-up, there were no significant differences in cardiac mortality and target lesion revascularization rate between octogenarians and non-octogenarians (7% vs. 3%, p=0.157, and 14% vs. 12%, p=0.682, respectively). Conclusions: Although octogenarian AMI patients had more atrial fibrillation, lower ejection fraction, higher high-sensitivity C-reactive protein and NT-pro BNP levels, and had more complex coronary lesions and more post-procedure no-reflow phenomenon, mid-term clinical outcomes were not different compared with non-octogenarian AMI patients.