A prospective randomized controlled trial of adjuvant chemotherapy for colorectal cancer was performed in forty-one institutions in Tokai district. In this study, effect of postoperative administration of mitomycin C (MMC) and followed by HCFU for more than 3 months (group B) was on the survival time compared with MMC alone (group A). Of 173 patients subjected to curative resection (group A = 80, group B = 93) for colorectal cancer, 148 patients including 69 cases of group A and 79 cases of group B were eligible for survival study. At six years after surgery, Kaplan-Meire's life table showed that the survival of group B was superior to that of group A (generalized Wilcoxon test: p = 0.0446). The difference of survival curves was more distinct (generalized Wilcoxon test: p = 0.0226) for patients of advanced stage those to have lymph node metastasis time and serosal inversion.