The Cooperative Study Group of Surgical Adjuvant Chemotherapy for Gastric Cancer adopted, as a second cooperative study, a prospective randomized trial on three groups: MMC alone, Ftorafur alone, and a combination of MMC and Ftorafur. The number of patients subjected to this analysis was 3033. The usefulness of long-term adjuvant chemotherapy was studied, based on a follow-up period of 4 years after surgery. No definite differences were observed in general. However, classified by prognostic factors, both the survival and disease free rates were improved in patients with stage III, n (+) ps (+) advanced cancer, to whom Ftorafur alone was administered for a long-term period. In patients who underwent of curative resection, the long-term administration of Ftorafur alone tended to prevent recurrence postoperatively, especially within the first two postoperative years. However the survival and disease free rates in the group receiving Ftorafur combined with MMC were higher than those of the group receiving Ftorafur alone. Moreover the combination of MMC and Ftorafur prolonged survival even in patients who did not undergo curative resection, and was found to be particularly useful in such patients, as designated by more than two prognostic factors.