To date, case-control studies on the association between methylenetetrahydrofolate reductase (MTHFR) and diffuse large B cell lymphoma (DLBCL) have provided either controversial or inconclusive results. To clarify the effect of MTHFR on the risk of diffuse large B cell lymphoma, a meta-analysis of all case-control observational studies was performed. The fixed effects and random effects model showed that the C677T polymorphism was associated with a risk of DLBCL among East Asian populations, and A1298C polymorphism was not associated with a risk of DLBCL among Caucasian and East Asian populations. Our pooled data suggest evidence for a major role of MTHFR C677T polymorphism in the carcinogenesis of DLBCL among East Asian populations.