Statistically significant findings between the null genotype of GSTM1 and gastric cancer risk was found in both non-smokers (OR = 1.370, 95% CI: 1.043-1.800, P < 0.024, P for heterogeneity = 0.028) and ever-smokers subgroups (OR = 1.558, 95% CI: 1.111-2.183, P < 0.010, P for heterogeneity < 0.001), respectively. This evidence concerns the gene GSTM1 and gastric cancer.