The 2010 Cardiopulmonary Resuscitation (CPR) Guidelines recommended therapeutic hypothermia for postcardiac arrest syndrome as a beneficial and effective treatment. However, the optimal temperature, method, onset, duration and rewarming rate, and therapeutic window remain unknown.Recent animal studies have shown that the sooner cooling is initiated after cardiac arrest, the better the outcome. Induction of hypothermia during cardiac arrest before return of spontaneous circulation (ROSC) (intra-arrest cooling) enhances its efficacy. In 2010, the Pre-ROSC IntraNasal Cooling Effectiveness (PRINCE) study and our clinical study of intra-arrest cooling concluded that intra-arrest cooling before ROSC was likely to have neurological benefits while protecting the myocardium for patients with out-of-hospital cardiac arrest.One of the most significant advances in CPR treatment in the past decade is therapeutic hypothermia. Although post-ROSC cooling has been shown to improve neurological outcome for patients with out-of-hospital cardiac arrest, intra-arrest cooling during CPR is likely to protect the myocardium from reperfusion injury and enhance neurological benefits.