Objective To explore the association between manganese superoxide dismutase (MnSOD) Val-9Ala polymorphism and breast cancer risk and to investigate the interaction with menopausal status by meta-analysis. Methods Such databases as The Cochrane Libtary (Issue1, 2010), Pubmed, CBM, CNKI and WanFang Data were searched from the date of their establishment to October, 2010, and the case-control studies of MnSOD Val-9Ala polymorphism and breast cancer risk were collected according to the inclusion and exclusion criteria. Then the quality of the included trials was assessed and meta-analysis was performed by RevMan 4.2.10 software. Results A total of 14 studies involving 17 842 patients were included. The results of meta-analyses showed no significant relation between MnSOD Val-9Ala polymorphism and the breast cancer susceptibility (Val/Ala vs. Val/Val: OR=1.04, 95%CI 0.93 to 1.17; Ala/Ala vs. Val/Val: OR=1.12, 95%CI 0.95 to 1.33; Ala/Ala vs. Val/Ala+Val/Val: OR=1.06, 95%CI 0.93 to 1.20; Val/Ala+ Ala/Ala vs. Val/Val: OR=1.06, 95%CI 0.94 to 1.10). However, in the subgroup analysis, the breast cancer risk significantly increased for premenopausal women (Val/Ala+Ala/Ala vs. Val/Val: OR=1.15, 95%CI 1.01 to1.31). Conclusion This meta-analysis suggests that the MnSOD Val-9Ala polymorphism is not significantly associated with the breast cancer susceptibility, but it may increase the risk of breast cancer in the presence of menopausal state.