The present study was undertaken to evaluate the effect of postoperative adjuvant chemotherapy for 232 cases of gastric cancer by a co-operative study group consisting of 21 hospitals. The present paper describes the side effects and the 2-year survival rates in patients. Side effects observed during long-term treatment with Futraful or UFT were considered to be minor, although incidence of toxicity in the UFT group was slightly higher than in the Futraful group. As for 2-year survival, elevated survival was found in stage III cases of poorly differentiated adenocarcinoma. This suggested that UFT is more useful than Futraful.