Microsomal epoxide hydrolase 1 (EPHX1) plays an important role in both the activation and the detoxification of polycyclic aromatic hydrocarbons and aromatic amines. Polymorphisms at exon 4 of the EPHX1 gene have been reported to be associated with variations in EPHX1 activity. Many studies have investigated the association between EPHX1 A139G polymorphism and lung cancer risk, but the impact of EPHX1 A139G polymorphism on lung cancer risk is not clear owing to the apparent inconsistence among those studies. This study aimed to identify the association between EPHX1 A139G polymorphism and lung cancer risk by performing a meta-analysis. We used the pooled odds ratio (OR) with its corresponding 95 % confidence interval (95 % CI) to explore the association. Finally, 26 studies with a total of 14,494 subjects were included into this meta-analysis. Meta-analyses of total studies showed the EPHX1 A139G polymorphism was associated with lung cancer risk under three genetic models (OR (G versus A) = 1.17, 95 % CI 1.04-1.31, P (OR) = 0.01; OR (AG versus AA) = 1.21, 95 % CI 1.06-1.37, P (OR) = 0.004; OR (AG + GG versus AA) = 1.22, 95 % CI 1.06-1.39, P (OR) = 0.005). Sensitivity analyses and subgroup analyses further identified the significant association between the EPHX1 A139G polymorphism and lung cancer risk. No evidence of publication bias was observed. Meta-analyses of available data supported the concept of EPHX1 A139G polymorphism as a genetic susceptibility factor for lung cancer.