ObjectiveTo systematically review the association between the insertion/deletion (I/D) polymorphism of angiotension-converting enzyme (ACE) gene and the athletes' performance in endurance sports. MethodsDatabases including PubMed, EMbase, CNKI, CBM, VIP, and WanFang Data were searched up to August 1st, 2015 to collect case-control studies about the association between ACE I/D polymorphism and the athletes' performance in endurance 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 37 case-control studies involving 3 032 athletes and 10 857 controls were included. The results of meta-analysis showed that significant association was found between ACE I/D polymorphism and the athletes' performance in endurance sports (DD+DI vs. Ⅱ: OR=0.75, 95%CI 0.67 to 0.83, P<0.01; DD vs. Ⅱ: OR=0.73, 95%CI 0.61 to 0.87, P<0.01; DI vs. Ⅱ: OR=0.74, 95%CI 0.66 to 0.83, P<0.01; D vs. Ⅰ: OR=0.85, 95%CI 0.77 to 0.94, P<0.01). Specifically, the ACE I/D polymorphism was significantly associated with the performance of male athletes in endurance sports (DD+DI vs. Ⅱ: OR=0.73, 95%CI 0.61 to 0.88, P<0.01; DD vs. Ⅱ: OR=0.75, 95%CI 0.60 to 0.93, P=0.01; DI vs. Ⅱ: OR=0.70, 95%CI 0.60 to 0.93, P<0.01; D vs. Ⅰ: OR=0.87, 95%CI 0.77 to 0.97, P=0.01). Subgroup analysis of ethnicity showed that, in Caucasians, except for genetic model DD vs. DI+Ⅱ, the other 4 genetic models were significantly associated with the athletes' performance in endurance sports (DD+DI vs. Ⅱ: OR=0.74, 95%CI 0.65 to 0.84, P<0.01; DD vs. Ⅱ: OR=0.72, 95%CI 0.58 to 0.90, P<0.01; DI vs. Ⅱ: OR=0.73, 95%CI 0.64 to 0.84, P<0.01; D vs. Ⅰ: OR=0.87, 95%CI 0.81 to 0.94, P<0.01); in Africans, significant associations with the athletes' performance in endurance sports were found in genetic model DD vs. DI+Ⅱ (OR=0.75, 95%CI 0.57 to 0.98, P=0.04), genetic model DD vs. Ⅱ (OR=0.62, 95%CI 0.42 to 0.92, P=0.02), and genetic model D vs. Ⅰ (OR=0.80, 95%CI 0.66 to 0.96, P=0.02); in Asians, no significant association was found between ACE I/D polymorphism and the performance of athletes of difference races in endurance sports. ConclusionCurrent evidence indicates that the ACE I/D polymorphism may be associated with the performance of athletes especially male athletes and the Caucasian subgroup in endurance sports. ACE allele D is negatively associated with the athletes' performance in endurance sports, while allele I is positively associated with the athletes' performance in endurance sports. Due to the quality limitations of included studies, more high quality case-control or cohort studies are needed to verify the above conclusions.