Ninety-six patients with colorectal cancer (stage B2-C) were randomized to the control arm or to receive adjuvant chemotherapy with folinic acid, FU and MMC. Ninety-three patients are evaluable. The median follow up is 12 months. The average time between surgery and the start of therapy is 28 days. Toxicity is evaluable in 36 of 41 treated patients. Four patients (10%) failed to complete the projected treatment due to toxicity. Toxicity observed in 208 courses of therapy was mostly gastrointestinal and hematological. No cases of treatment related death or cancer-associated hemolytic uremic syndrome (C-HUS) were reported. The average relative dose intensity (rDI) of the projected treatment was 82.6%. Our study is ongoing and further patients are required to achieve statistically significant results.