The therapeutic results of the method II of the second study of the Cooperative Study Group of Surgical Adjuvant Chemotherapy for Colorectal Cancer in Japan were retrospectively reviewed and the relations of the 3-year survival rate to the dose of UFT per body weight as well as per kg of the patient and discontinuation of the treatment with UFT were investigated. The dose per day of UFT was randomly divided into group C (treated with UFT 600 mg/body/day) and group D (treated with UFT 400 mg/body/day for 12 months) by the envelope method. The 3-year survival rate of the patients whose body weight was 50 kg or more was higher than in the patients weighting less than 50 kg. The 3-survival rate of the patients treated with UFT from 8 to less than 12 mg/kg was the highest, while that of the patients treated with UFT of more than 12 mg/kg was the lowest. However, no statistical difference was observed between the two groups. The same results were observed in carcinoma of the colon and rectum, respectively. The findings indicated that the administration of excess amount of UFT was not effective. The relation between the 3-year survival rate and discontinuation of treatment with UFT was investigated at 6, 9 and 12 months after administration with UFT. The prognostic background factors of the C-group and the D-group were compared, but no difference was observed between the 2 groups at 9 months after administration. The 3-year survival rate of the patients treated continuously with UFT was higher than that of discontinued administration. The difference was especially evident in carcinoma of the colon, and good results were observed in cases treated continuously than in discontinued cases in both C- and D-groups.