Objective To explore the clinical significance of cytokeratin(AE1/AE3) immunohistochemical staining in detecting the lymph node micrometastasis of gastric cancer.Methods Immunohistochemical S-P method was used to examine AE1/AE3 in 118 lymph nodes in 64 cases of primary gastric cancer.Results Among 118 lymph nodes,micrometastasis was found in 13 lymph nodes of 8 patients with primary gastric cancer by AE1/AE3 staining.The positive rate of micrometastasis was 12.5% and the positive rate of lymph nodes was 11.02%.The incidence of micrometastasis was related with the depth of invasion,and in the cancer with deep invasion,the positive rate of micrometastasis was higher than that in the cancer with superficial invasion(P