We retrospectively examined the long-term results of adjuvant chemotherapy with mitomycin-C (MMC) in 50 patients with gastric carcinoma invading the adjacent organs. All patients underwent gastrectomy and en bloc multiple resection of the invaded organs, with the intent of a potential cure. Evidence of direct invasion was confirmed histologically. These patients were classified into 3 groups, according to the dose schedule of MMC: 12 received prolonged, intermittent administration of the drug, in a total dose of 40 mg or more (group A); 19 were given a bolus injection at the time of surgery and/or on the following day, in a total dose of less than 40 mg (group B), and 19 were given no anticancer drugs (group C). These 3 groups were comparable with regard to various prognostic factors. The 5-year survival rates were 50, 32 and 17% in groups A, B and C, respectively. There was a statistical difference in survival between groups A and C (p less than 0.05). These results indicate that extensive en bloc resection plus intensive adjuvant chemotherapy prolong the survival time for those with gastric carcinoma invading the adjacent organs.