Introduction: Pre-hospital capabilities are minimally developed in Vietnam; therefore, the prognosis of OHCA might differ from that of other countries. The aim of this study was to investigate survival rate from OHCA and potential determinants of the chain of survival following an OHCA in a developing country. Hypothesis: Understanding the country-specific etiologies and the disease risk and prognosis of OHCA are crucial for reducing mortality in Vietnam, as well as in other countries that face challenges in clinical practice owing to limited medical resources. Methods: This is a multi-center prospective observational study of OHCA patients (age>18 years) presenting to the ED of three tertiary hospitals from February 2014 to December 2018. Factors associated with survival following OHCA were collected and compared among types of pre-hospital care transportation and between survival and non-survival to admission. Factors for survival to admission were assessed using logistic regression analysis. Results: Among 590 OHCA patients (male, 74.6%; age, 56.1±17.2 years), we observed low rates of survival to admission (24.2%) and discharge (14.1%). Of total patients, 67.8% occurred at home, 79.4% witnessed by bystanders, 124/555 (22.3%) received bystander CPR, a minority of patients (8.64%) was conveyed by EMS, and 49/152 (32.2%) received pre-hospital defibrillation. Multivariate analysis revealed that past medical history (PMH) of respiratory disease (OR, 3.128; 95% CI, 1.197-8.173), pre-hospital defibrillation (OR, 3.904; 95% CI, 1.540-9.898), pre-hospital advanced airway (OR, 3.441; 95% CI, 1.203-9.844) and ROSC at ED (OR, 2.891; 95% CI, 1.030-8.115) were independent factors for survival to admission. Following OHCA with cardiac etiology, EMS use (OR, 0.203; 95% CI, 0.044-0.935) was also an independent factor for survival to admission. Conclusions: This was a highly selected cohort of OHCA patients presenting to the ED. Many OHCA victims in Vietnam do not come to the ED. PMH of respiratory disease, pre-hospital defibrillation and advanced airway, and ROSC at ED were independent factors predicting survival to admission. EMS use was also an inverse and independent predictor of survival to admission among patients following OHCA with cardiac etiology.