Purpose: To evaluate the quality of prehospital CPR (cardiopulmonary resuscitation) performed by 119 rescue personnel and bystanders in Seoul and to recognize the present problems in the pre-hospital emergency medical service system (EMS). Methods: We enrolled all patients in cardiac arrest visiting the emergency rooms of 9 university hospitals in Seoul via 119 rescue services from 16 October to 26 November 2006, prospectively investigating the environments in which arrest occurred and the factors associated with CPR. Results: Among 73 patients, the most common place of arrest was in the home(45.2%), CPR by bystander was performed in 8 cases(10.7%), endotracheal intubation by EMS personnel was performed in 10 cases(14.1%). Average time from call to CPR was 11.9 minutes and the number of discharges alive was 3 cases(4.1%). Conclusion: To improve the rate of alive discharges, development of CPR education program for lay rescue, education in basic and advanced life support, and management of quality for EMS personnel are needed