Background/Aims: Lymph node micrometastasis could be detected by immunohistochemical staining but not by conventional H&E staining. We investigated the usefulness of immunohistochemical staining in evaluation of lymph node metastasis, and examined the role of p53 protein expression in the detection of lymph node micrometastasis. Methods: H&E staining and immunohistochemical staining using antibodies against cytokeratin and CEA were performed in 509 lymph nodes resected from 19 patients with gastric adenocarcinomas. The expression of p53 was investigated for primary tumors and 401 lymph nodes obtained from 16 patients with gastic cancer. Results: Metastasis was confirmed in 131/509 (25.7%) lymph nodes by H&E staining, in 186/509 (36.5%) by immunohistochemical staining (cytokeratin, 186; CEA, 30), and in 187/509 (36.7%) by combined analysis. Micrometastasis was identified in 56 lymph nodes (14.8%). Five of seven patients who had H&E-negative lymph nodes showed micrometastasis, and all were poorly differentiated or signet ring cell type and diffuse type of carcinoma. P53 protein was more frequently expressed in metastasis-positive nodes than negative nodes (24.3% vs. 1.2%, p<0.005). However, the expression of p53 was observed in only 7.0% of lymph nodes with micrometastasis. Conclusions: Immunohistochemical staining for cytokeratin is useful for detection of lymph node micrometastasis, especially in poorly differentiated and diffuse type adenocarcinomas. P53 expression in lymph nodes is not so useful for identification of lymph node micrometastasis. (Korean J Gastroenterol 2001;37:327-335)