The relationship between metastatic lesions and the degree of appearance of plasma cells In regional lymph nodes affected by carcinoma of the stomach was observed In this study. At the initial stage of metastasis to a lymph node, numerous plasma cells were found In the lymphatic parenchyma adjacent to the metastatic lesion. As the metastatic lesions Increased, the number of plasma cells decreased. Few plasma cells appeared in the intact lymph node distant from the primary lesion of carcinoma. It Is suspected that this phenomenon may be tentatively explicable from the antigen‐antibody reaction at the Initial stage of metastasis in a lymph nod