Seventy-three patients with Dukes' B2 and C colorectal cancer were randomized to adjuvant therapy after radical surgery. One group was treated with chemotherapy either alone or in combination with radiotherapy (RC). The second group was treated by chemotherapy (with or without radiotherapy) plus MER/BCG (RCM). In patients with Dukes' C disease, the survival at 54 months and the disease-free interval up to 24 months were significantly better in the RCM than in the RC subgroup. There were no significant differences in the survival and disease-free interval between RC- and RCM-treated patients with Dukes' B2 disease. Entry of additional patients and further follow-up are needed before we can decide whether the combination of RCM increases the cure rate in Dukes' C cancer or merely delays recurrence and prolongs survival.