All patients who had an out-of-hospital cardiac arrest between 1 June 2008 and 31 July 2010 be admitted in emergency department of Thong Nhat Hospital. Result: We have 180 patients who presented with an out-of-hospital cardiac arrest in this period. Conclusion: Our research shows that in elderly population, these OHCA cases are result of patient's medical history of heart disease, diabetes, chronic lung disease, and cancer.