Background:Therapeutic hypothermia has been recommended for the treatment of cardiac arrest patients who remain comatose after the ret of spontaneous circulation.The aim of this study was to evaluate the effectiveness and safety of mild hypothermia on patients with cardiac arrest by conducting a meta-analysis.Methods:The relevant trials were searched in Cochrane Library,PubMed,Web of Science,Embase,CNKI and Wan Fang Data from the date of their establishment to October 2014.Thereafter,the studies retrieved were screened based on predefined inclusion and exclusion criteria.Data were extracted,and the quality of the included studies was evaluated.A meta-analysis was conducted using the Cochrane Collaboration Review Manager 5.2 software.Results:Six randomized controlled trials involving 531 cases were included,among which 273 cases were assigned to the treatment group and the other 258 cases to the control group.The meta-analysis indicated that mild hypothermia therapy after cardiac arrest produced significant differences in survival rate (relative risk [RR] =1.23,95％ confidence interval [CI]:1.02-1.48,P =0.03) and neurological function (RR =1.33,95％ CI:1.08-1.65,P =0.007) after 6 months compared with normothermia therapy.However,no significant differences were observed in the survival to the hospital discharge (RR =1.35,95％ CI:0.87-2.10,P =0.18),favorable neurological outcome at hospital discharge (RR =1.53,95％ CI:0.95-2.45,P =0.08) and adverse events.Conclusions:The meta-analysis demonstrated that mild hypothermia can improve the survival rate and neurological function of patients with cardiac arrest after 6 months.On the other hand,regarding the survival to hospital discharge,favorable neurological outcome at hospital discharge,and adverse events,our meta-analysis produced nonsignificant results.