ObjectiveTo systematically review the association between the insertion/deletion (I/D) polymorphism of angiotension-converting enzyme (ACE) gene and the athletes'performance in mixed sports. MethodsDatabases including PubMed, EMbase, CNKI, CBM, VIP, and WanFang Data were searched from inception to August 1st, 2015 to collect case-control studies about the association between ACE I/D polymorphism and the athletes'performance in mixed sports. Two reviewers independently screened literature, extracted data and assessed the risk of bias of included studies. Then, meta-analysis was performed using RevMan 5.3 software. ResultsA total of 13 case-control studies involving 888 athletes and 3 871 controls were included. The results of meta-analysis showed that significant association was found between ACE I/D polymorphism and the athletes'performance in mixed sports (DD vs. DI+II: OR=0.71, 95%CI 0.59 to 0.84, P < 0.01; DD vs. II: OR=0.69, 95%CI 0.54 to 0.87, P < 0.01; D vs. I: OR=0.82, 95%CI 0.72 to 0.92, P < 0.01). Specifically, the ACE I/D polymorphism was significantly associated with the performance of male athletes in endurance sports (DD vs. DI+II: OR=0.71, 95%CI 0.57 to 0.89, P < 0.01; DD vs. II: OR=0.70, 95%CI 0.51 to 0.95, P=0.02; D vs. I: OR=0.80, 95%CI 0.69 to 0.94, P=0.01). However, this significant association was not found in football and middle-distance running sports. Subgroup analysis of ethnicity showed that, the ACE I/D polymorphism was significantly associated with the performance of Caucasian (DD vs. DI+II: OR=0.71, 95%CI 0.59 to 0.87, P < 0.01; DD vs. II: OR=0.69, 95%CI 0.54 to 0.90, P=0.01; D vs. I: OR=0.80, 95%CI 0.71 to 0.92, P < 0.01) and Asian (DD vs. DI+II: OR=0.42, 95%CI 0.20 to 0.89, P < 0.01) athletes in endurance sports, but not with African athletes. ConclusionsCurrent evidence indicates that the ACE allele D is negatively associated with the athletes'performance in mixed sports. Due to the limitations of included studies, more high quality case-control or cohort studies are needed to verify the above conclusion.