BACKGROUND: Previous studies have suggested that percutaneous coronary intervention (PCI) is effective in improving in-hospital survival in very elderly patients. The objective of this study was to evaluate effect of emergency PCI on the in-hospital mortality of very elderly (���80 years) patient with acute myocardial infarction (AMI) admitted to coronary care unit. METHODS: The study was a retrospective observational study of all consecutive patients admitted to an intensive coronary care unit in the Chonnam national university hospital with the diagnosis of AMI from 2006 to 2008. A total of 106 patients undergoing emergency PCI and 32 patients not undergoing PCI were included in the present analysis. RESULTS: We compared the baseline and procedural characteristics and clinical outcome between the 2 groups . there was not significant difference in age and sex (Group I, Group II). Ejection fraction (EF), heart failure (HF), renal failure, cerebrovascular accident (CVA), chronic obstructive pulmonary disease (COPD), and pulmonary edema were different between two groups. PCI did not influence in hospital mortality (p value= 0.43). In logistric regression analysis, the factor influencing in-hospital mortality was use of intra-aottic balloon pump (IABP) and ventilator (IABP: OR=0.051, 95% CI=0.01-0.266, ventilator use: OR=0.198, 95% CI=0.04-0.979) CONCLUSION: The results indicated that emergency PCI has not a preventative effect on in-hospital mortality in elderly patients with AMI. The factor influencing in-hospital mortality was use of intra-arotic balloon pump and ventilator.