BACKGROUND Published data on the association between present/null polymorphism of glutathione S-transferase M1 (GSTM1) and breast cancer risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis in the Chinese population was performed. METHODS PubMed, Springer Link, Ovid, Chinese Wanfang Data Knowledge Service Platform, Chinese National Knowledge Infrastructure (CNKI), and Chinese Biology Medicine (CBM) were searched. Crude odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association between the GSTM1 present/ null polymorphism and breast cancer risk. RESULTS A total of 17 studies including 5323 breast cancer cases and 7196 controls were involved in this meta-analysis. Overall, a significant association (OR = 1.28, 95%CI: 1.09 - 1.51) was found between the null GSTM1 and breast cancer risk when all studies in Chinese population were pooled into the meta-analysis. In subgroup analyses stratified by geographic areas and source of controls, the same results were observed in mainland China (OR = 1.42, 95% CI = 1.12 - 1.81) and hospital-based studies (OR = 1.55, 95% CI = 1.20 - 2.00). CONCLUSIONS This meta-analysis suggests that the GSTM1 null genotype is a low-penetrant risk factor for developing breast cancer in the Chinese population.