Background: It is well known that hyperglycemia is associated with poor outcomes in critically ill patients. We investigated the association between blood glucose level at admission and outcomes of patients treated with therapeutic hypothermia after cardiac arrest. Methods: We performed a multicenter retrospective registry-based study of adult OHCA patients treatedwith TH presenting to 24 hospitals across South Korea during the period from January 2007 to December2012. We examined the association of blood glucose at admission on survival and neurologic outcome at hospital discharge. Neurologic outcome was assessed with Cerebral Performance Category (CPC) and favorable neurologic outcome was defined CPC score of 1 and 2. Results: Of a total of 930 OHCA patients entered in the registry, 883 patients were analyzed in this study. The mean age of the sample was 56.7±16.2 years, 69.5% of subjects were male and mean blood glucose at admission was 14.1±7.0 mmol/L.In univariate analysis there were an association between glucose level at admission and favorable neurologic outcome (OR, 0.958; 95% CI, 0.934-0.983) and survival (OR, 0.965; 95% CI, 0.945-0.986). After adjustment for sex, age, history of diabetes mellitus, hypertension, renal disease and stroke, time from arrest to ROSC, initial rhythm, witness status, bystander CPR, cause of arrest and adrenaline, this association still remained: for favorable neurologic outcome (OR, 0.958; 95% CI, 0.921-0.997) and for survival (OR, 0.974; 95% CI, 0.952-0.996). Conclusion: These results show that blood glucose level at admission is associated with survival and favorable neurologic outcome at hospital discharge in patients treated with therapeutic hypothermia after cardiac arrest. Blood glucose level at admission may be a surrogate marker of ischemic insult severity during cardiac arrest. However, randomized controlled evidences are needed to address the significance of a tight glucose control during therapeutic hypothermia after cardiac arrest.