ObjectiveTo systematically review the tumor necrosis factor-α (TNF-α) -308G/A polymorphism and the risk of inflammatory bowel disease (IBD). MethodsAll eligible case-control studies published up to Jan 25th 2015 were identified by searching PubMed, EMbase, CNKI, WanFang Data, CBM and VIP databases. Two reviewers independently screened the studies according to the inclusion and exclusion criteria, extracted data and assessed methodological quality of included studies. Then, meta-analysis was performed using RevMan 5.2 and Stata 12.0 softwares. ResultsA total of 20 studies involving 2 860 IBD cases and 5 033 controls were included. The results of meta-analysis showed:Compared with the wild genotype GG, genotype GA, AA and genotype GA+AA were associated with susceptibility of ulcerative colitis (UC) (GA vs. GG:OR=1.45, 95%CI 1.02 to 2.07, P=0.04; AA vs. GG:OR=2.01, 95%CI 1.32 to 3.05, P=0.001; GA+AA vs. GG:OR=1.51, 95%CI 1.07 to 2.13, P=0.02); Compared with genotype GA+AA, genotype AA increased the risk of UC (AA vs. GA+GG:OR=1.92, 95%CI 1.26 to 2.91, P=0.002); allele A did not increase the risk of UC; Compared with genotype GG, genotype AA increased the risk of Crohn disease (CD) (AA vs. GG:OR=1.49, 95%CI 1.07 to 2.08, P=0.02); Compared with genotype GA+GG, while genotype AA increased the risk of CD (AA vs. GA+GG:OR=1.50, 95%CI 1.08 to 2.09, P=0.02); genotype GA, GA+AA and allele A did not increase the risk of CD. In stratification analyses by ethnicity, we found that the TNF-α-308G/A was significat associated with IBD in Europeans. ConclusionCurrent evidence indicates that TNF-α-308G/A polymorphism is associated with the susceptibility of IBD, genotype GA, AA and GA+AA increase the risk of suffering from UC while genotype AA increase the risk of suffering from CD. Due to the limited quantity of the included studies, more researches are needed to verify the above conclusion.