Purposes: Mild therapeutic hypothermia (TH) is provided to the patients who cannot obey verbal command after cardiac arrest (CA). In Korea, emergency medical services (EMS) supply basic life support (BLS) including chest compression, airway management and defibrillation for out-of-hospital cardiac arrest patients. Sometimes, there is pre-hospital return of spontaneous circulation (ROSC). So we aimed to investigate the clinical outcomes of pre-hospital ROSC patients who were implemented TH, and whose cardiac arrest cause was cardiac origin. Methods: A retrospective review of comatose survivors who got ROSC before hospital arrival after CA was performed in two tertiary general hospitals between Jan 2010 and July 2014. Non cardiac origin CA, patients who did not receive TH and patients who recovered consciousness were excluded. Results: Thirty-one patients were included in this study. Twenty-eight patients (90.3%) were male, age was 49.5 years and only 5 patients (16.1%) were over 65 years. Nineteen (61.3%) had no underlying disease. Shockable rhythm was in 93.5%, witness arrest was in 93.5%, and bystander BLS was performed in 74.2%. Only 1 patient died due to multi-organ failure, and the rest 30 patients were discharged as CPC 1. The most common final diagnosis was myocardial infarction (35%), idiopathic VF/VT (32%). Conclusions: Pre-hospital ROSC presumed cardiac origin occurs occasionally in relatively young, healthy patients. They were almost shockable rhythm, witness arrest and show good neurologic outcome.