In short, there were significant statistical associations between hMLH1 methylation and lymph node metastasis (OR = 1.53, 95%CI = 1.04–2.26, P = 0.03, fixed-effect model), microsatellite status (OR = 15.33, 95%CI = 9.26–25.36, P < 0.001, fixed-effect model) and low hMLH1 protein expression (OR = 37.86, 95%CI = 18.03–79.50, P < 0.001, fixed-effect model) in gastric cancer patients, but not with Lauren classification (OR = 1.48, 95%CI = 0.86–2.55, P = 0.16, fixed-effect model) or HP infection status (OR = 1.18, 95%CI = 0.69-2.01, P = 0.54, fixed-effect model). The gene discussed is MLH1; the disease is metastatic malignant neoplasm in the lymph nodes.