Background: Coronary artery disease (CAD) is the leading cause of sudden cardiac death (SCD) in western countries. However, the etiology and prognosis of SCD may be different according to the races. This study was performed to reveal the differences of the causes of out-of-hospital SCD and prognosis in Korean patients. Methods: Among the 253 out-of-hospital aborted SCD patients from 1997 to 2010, 94 patients (male: 77, age: 50 짹 17 years), who survived for at least 24 hours to undergo full medical studies, were enrolled in this study. The etiology of the SCD, neurologic outcome and survival were evaluated. Results: Of the 94 patients, 25 (27%) had CAD as the cause of SCD. Of the 70 patients without fixed CAD, 13 (14%) had ion-channelopathies, 11 (12%) cardiomyopathies, 9 (10%) coronary artery spasm, 4 (4%) bradycardia dependent Torsade de pointes, and 2 (2%) proarrhythmia. The underlying cause of SCD was not revealed in 30 (32%) patients despite aggressive work up and regarded as idiopathic. The incidence of SCD by CAD was relatively lower (27%) than the published data in western countries. Mean age was greater (58 짹 17 vs. 47 짹 16 years, p = 0.004) and ejection fraction was lower (39 짹 8 vs. 58 짹 14%, p = 0.002) in patients with CAD. There was no significant difference in other clinical parameters. Survival discharge and neurologic outcome were evaluated in 91 (92%), and 6 month survival rate was evaluated in 82 (87.2%) patients. The median follow up duration of 759 days (range: 1 day – 5652 days). In the 91 patients, survival discharge rate and 6 month survival rate were 81% and 76%, respectively. Compared to patients with CAD, the patients with non CAD etiology (including coronary artery spasm) had better survival discharge (88% vs. 59%, p=0.014) and 6 month survival rate (82% vs. 55%, p = 0.014). Physical disability by hypoxic brain injury was more frequent in patients with CAD than those without CAD (61% vs. 31%, p = 0.011). In logistic regression analyses, non-CAD etiology was related with better neurologic and survival outcomes than CAD etiology. Conclusions: In the out-of-hospital SCD survivors over initial 24 hours, more than two third had non-CAD etiology in Korean patients. Patients with non-CAD etiology had better prognosis than those with CAD.