BACKGROUND: Previous studies have suggested that percutaneous coronary intervention (PCI) is effective in improving in-hospital survival very elderly patients. The factors influencing in hospital mortality in the patient of the very elderly with acute myocardial infarction admitted to an intensive coronary care unit (CCU) is remained unknown. The objective of this study was to evaluate the factor influencing in-hospital mortality of very elderly (���80 years) patient with AMI admitted to a CCU. METHODS: The study was a retrospective observational study of 134 patients of octogenarians admitted to an intensive coronary care unit in the Chonnam National University Hospital with the diagnosis of AMI from 2006 to 2008. These patients are divided into two groups according to survival: 114 survived patients (85.1%, 83.9짹3.5, 53 male) and 20 moribund patients (84.7짹3.4, 10 male). RESULTS: We compared the baseline and procedural characteristics and clinical outcome between the two groups. There were no significant differences in age and sex, CCU admission duration, ejection fraction, vessel of revascularization, renal failure, arrhythmia, heart failure, diabetes mellitus, hyperlipidemia and smoking between two groups. Success rate of PCI was 86.4% (89/103), however PCI performance did not influence in-hospital mortality (p=0.43). Cardiogenic shock, intra-aortic balloon pump (IABP), inotropics, Killip class, use of ventilator were different between two groups. In logistic regression, the factors influencing in-hospital mortality were uses of IABP (OR=0.051; 95% CI =0.01-0.266) and ventilator (OR=0.198 95% CI=0.04-0.979). CONCLUSION: Survival rates of octogenarian and success rate of PCI were relatively high and the factors influencing mortality were use of IABP and ventilator.