Objective To explore the expressions ofβ-catenin in gastric adenocarcinoma primary tumors and metastatic lymph nodes,and to determine if it is associated with infiltration degree and whether it can provide the basis for gastric cancer metastasis.Methods The expressions ofβ-catenin were detected in 156 patients with gastric adenocarcinoma specimens,40 cases with the corresponding lymph nodes and 12 cases of normal gastric tissues by the method of immunohistochemistry.The expressions ofβ-catenin in gastric adenocarcinoma and corre-sponding lymph node metastases were analysed.The relationship between the expression of β-catenin and the clinical pathological features of gastric adenocarcinoma was ascertained,and difference between them was observed.Results The positive expression rate ofβ-catenin in normal gastric tissue membrane was 100.0%(12/12).The expression rate ofβ-catenin was 29.5%(46/156)in adenocarcinoma cell membrane,and it was 10.0%(4/40)in metastatic lymph nodes cell membrane.The positive expression ofβ-catenin was not associated with patient′s age(χ2 =2.160,P=0.142),gender (χ2 =1.229,P=0.268),but it was associated with tumor infiltration degree (χ2 =4.032,P=0.045 ),degree of tumor differentiation (χ2 =6.093,P=0.048),tumor stage (χ2 =4.591,P=0.032),and metastasis lymph nodes (χ2 =4.485,P=0.034).The incidence of abnor-mal or loss expression ofβ-catenin in gastric adenocarcinoma metastatic lymph nodes was higer than that in gastric adenocarcinoma (χ2 =6.362,P=0.012).Conclusion The expression of β-catenin will be a great help to judge the biological behaviors such as the malignant degree of tumor and the capacity of tumor invasion and metas-tasis.