In order to evaluate the effect of anticancer drugs on the metastatic lesions of the regional lymph nodes from stomach cancers removed after oral administration of 5-FU emulsion, histological examinations of the specimens obtained from 107 surgical cases were carried out. In additional 13 cases with gastric cancer, the active 5-FU concentrations in the regional lymph nodes were determined. The effect of 5-FU emulsion in metastatic lesions as determined was histologically classified into Grades 0 to III according to the severity and extent of damaged cells and cell nests Grades II and III were judged to demonstrate the beneficial effect of the 5-FU emulsion. Such changes were identified in 62.0 per cent of the 242 metastatic lymph nodes, and the effectiveness increased as the total dose of the 5-FU emulsion administered increased (50.9 per cent for 5,000 mg or less, 70.9 per cent for 5,000 to 6,000 mg, and 72.7 per cent for 6,000 mg or more). The rate of effectiveness also varied with the histological type of the primary carcinoma, i.e. the differentiated type being more sensitive. The mean active 5-FU level in the regional lymph nodes was higher after the administration of 5-FU emulsion than of 5-FU solution supporting the earlier animal experiments.