RAD51 plays a key role in homologous recombination repair of double-stranded DNA breaks which may cause chromosomal breaks and genomic instability. We performed a meta-analysis of 9 epidemiological studies involving 13,241 cases and 13,203 controls that examined the association between RAD51 135G>C polymorphism and breast cancer. No significant association of RAD51 135G>C polymorphism with breast cancer was found in overall and European populations. However, after the studies which did not fulfill Hardy-Weinberg equilibrium were excluded, we observed an overall significant increased breast cancer risk (for the recessive model CC vs. GG/CG: OR = 1.35, 95% CI = 1.05-1.74, P (heterogeneity) = 0.06). In summary, our meta-analysis suggested the RAD51 135G > C polymorphism may contribute to breast cancer susceptibility.