In order to evaluate the efficacy of surgical adjuvant chemotherapy in patients undergoing gross curative resection for colorectal cancer (excluding m and sm cancer), a randomized controlled study was conducted from January, 1982 to October, 1983. Four hundred and ninety-one institutions participated in this study. The schedules for drug administration differed according to each district. In the Hokkaido and Shikoku districts, the patients were divided into the following two groups, one was a combination of ACNU and Futraful (FT) and the other was FT only. In the Chubu and Kinki districts, three groups were studied, namely those receiving a combination of ACNU and FT, those receiving FT only and those given no adjuvant chemotherapy. In the Tohoku and Kanto districts, a combination of MMC and FT and administration of FT only were studied. In the Chugoku and Kyushu districts, the patients were divided into a combination of ADM and FT, and FT only group. Among the 3,926 registered cases, 3,421 cases were valid for the study. As to the background factors, there were no significant differences among the groups in each district. There were no significant differences in one-year survival rates and one-year disease-free rates. No serious adverse effects were observed in any of the groups.