Introduction: The aim of this study was to evaluate the effect of aging on the in-hospital outcomes and efficacy of this treatment in patients with ST elevation myocardial infarction (STEMI) who underwent primary percutaneous coronary intervention (PCI). Materials and Method: 322 consecutive patients with acute STEMI undergoing primary PCI between December 2007 and July 2010 were included in the study. Analyses were performed retrospectively. Patients were divided into two groups according to age. The older group consisted of patients aged 65 or over and the younger group consisted of patients aged below 65 years. The baseline characteristics, primary PCI success and in-hospital outcomes (deaths, recurring infarctions, stroke and major bleeding) were compared between the two groups. Results: There were more women, more patients with hypertension, and with diabetes mellitus in the older group when compared with the younger group. Time from symptom onset to hospital admission was significantly longer in older group. Primary PCI success was similar between the two groups. In-hospital death and recurrent myocardial infarction were observed more frequently among elderly patients. Conclusion: Our results confirmed that, in the elderly there is increased risk of death and complications due to myocardial infarction. Primary PCI is a safe and effective reperfusion strategy in this high-risk population.