This paper is aimed to assess the effects of red blood cell (RBC) transfusion on clinical outcomes in cardiac surgery. Trials were identified by computer searches of the Pubmed,MEDLINE,Cochrane Library (Issue10,2012),from January 1980 to October 2012. References in identified trials and review articles were checked and experts contacted to identify any additional trials. The homogeneous randomized controlled trials (RCTs) were analyzed with RevMan 5.1 software. Five trials involving a total of 1,203 patients were identified. The results of meta-analyses showed that restrictive transfusion strategies reduced the risk of receiving a RBC transfusion (MD=-1.46,95% CI -1.18--1.1) and the volume of RBCs transfusion (RR=0.69,95% CI 0.53-0.89). No significant difference was noted between the two strategies in terms of mortality,adverse events and hospital or intensive care length of stay. Based on the results mentioned above, one can draw a conclusion that restrictive transfusion strategies reduced the risk of receiving RBC transfusion and the volume of RBCs transfused. Restrictive transfusion strategies did not appear to impact on the rate of adverse events and hospital or intensive care length of stay, compared to liberal transfusion strategies.