Background: The aim of this study was to investigate the association between adverse events (AEs) recorded during therapeutic hypothermia (TH) and advanced critical care after out-of-hospital cardiac arrest (OHCA) and poor neurological outcome in an Asian country where withdrawal of life support by prognostication is not yet permitted. Methods: We performed a multicenter retrospective registry-based study of adult OHCA patients treated with TH presenting to 24 hospitals across South Korea during the period from January 2007 to December 2012. The primary outcome was poor neurological outcome, defined as Cerebral Performance Category (CPC) of 3-5, at hospital discharge. AEs and concomitant treatments during cooling, rewarming and advanced critical care period were entered one at a time into the best predictive model for poor neurological outcome for evaluation of association. Results: Of a total of 930 OHCA patients entered in the registry, 704(76%) with a full set of adverse events and covariates for multivariate modeling were included in the analysis. Patients with a poor neurological outcome were 476 [CPC3=50(11%), CPC4=214(45%), CPC5=212(44%)]. Hyperglycemia (46%), hypokalemia (31%) and hypotension (29%) during cooling, and hypotension (22%) during rewarming were common AEs, whereas bleeding were rare (2%). During advanced critical care period, pneumonia (40%), hypoglycemia (23%), myoclonus (22%) and seizure (22%) were common AEs. Sepsis, hypoglycemia, myoclonus, seizure, anticonvulsants and continuous renal replacement therapy during advanced critical care were associated with poor neurological outcome (Table). Conclusion: AEs were common during TH but not associated with poor neurological outcome at hospital discharge. Sepsis, hypoglycemia, myoclonus, seizure, anticonvulsants and continuous renal replacement therapy during advanced critical care period were associated with poor neurological outcome at hospital discharge in our study.