Background: Outcome after out of hospital cardiac arrest (OHCA) is mostly determined by the degree of hypoxic brain damage with unfavourable neurological result in more than 50% of cases. Neuron-specific enolase (NSE) is proposed as a predictor of neurological outcome after OHCA, however this is not definitely established. Therefore we conducted a study investigating the association between NSE levels and neurological outcome in patients treated with mild therapeutic hypothermia (MTH). Methods: Data from patients after cardiac arrest receiving MTH (n=94) were analysed from January 2006 to December 2012 in a prospective observation cohort study. Neurological outcome was classified according to the Pittsburgh cerebral performance category (CPC). Results: Mean age was 61±14year (71% men), median time to return of spontaneus circulation was 24,5min. Survival was 72%, 63% from them with good neurological status (CPC 1+2). NSE levels were significantly lower in survivers. The cut off value for absolute NSE levels in patients with unfavourable outcome (CPC 3-5) 72 hours after cardiac arrest was 80ug/l, with an area under the curve of 0,74 (senzitivity 65%, specificity 100%). There was a significant correlation between NSE at 72 hours and lactate (p=0,04), pH (p=0,06) upon admission however these were not independent predictors of outcome. We didn´t observe any correlation between neurological status and NSE level difference on admission and after 72 hours. There were no significant differences of NSE levels between pts. with ischemic vs. nonischemic etiology, shockable vs nonshockable rythm and pts with mydriasis vs miosis on admission. Conclusion: Our analysis showed, that NSE cut off level of 80ug/l was the most reliable predictor of poor neurological outcome after OHCA treated with mild theraputic hypothermia.