ObjectiveTo evaluate the association between tumor necrosis factor alpha (TNF-α) gene -308G/A polymorphism and the risk of endometriosis (EM). MethodsDatabases including PubMed, EMbase, CBM, CNKI, VIP, and WanFang Data were searched to collect case-control studies about the association between TNF-α gene -308G/A polymorphism and the risk of EM from inception to October 2014. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. Then Meta-analysis was performed by using Stata 12.0 software. ResultsA total of seven case-control studies were included, which involved 687 patients and 877 controls. The results of meta-analysis showed that, AA genotype carriers presented 2.06-fold (OR=2.06, 95%CI 1.10 to 3.83, P=0.02) and 1.94-fold (OR=1.94, 95%CI 1.18 to 3.18, P<0.01) higher risk of EM than GG genotype carriers and AG+GG genotype carriers, respectively; but sensitivity analysis showed that the robustness of these results was unstable. No statistical significance was found in the allele model, co-dominant model, and dominant model (A vs. G: OR=1.37, 95%CI 0.87 to 2.17, P=0.18; AG vs. GG: OR=1.09, 95%CI 0.77 to 1.53, P=0.63; AA+AG vs. GG: OR=1.29, 95%CI 0.95 to 1.77, P=0.11). While excluding studies that controls were not in HWE, no significant association was observed in these five genetic models; and no significant association was found in the results of subgroup analysis by ethnicity. ConclusionThe AA genotype of TNF-α gene -308G/A polymorphism might contribute to the risk of EM, but the association between other genotypes and EM susceptibility is unclear. In addition, due to the limited quantity and quality of included studies, more high quality studies are needed to verify the above conclusion.