To assess tolerance according to the WHO classification of adjuvant and palliative chemotherapy for colorectal cancer. Methods: Prospective study including 40 patients with colorectal adenocarcinoma treated with chemotherapy over a period of 4 years. Results: Forty patients , mean age 56 years were included. 71 lines of chemotherapy were administered, side effects were noted in 59 lines (83%), severe toxicities were mainly observed with Folfox 4 and Folfiri type chemotherapy. Side effects, all toxicities combined, were more frequently observed with palliative chemotherapy 66% (p=0.04) and with advanced stages (stage IV) 44% (p=0.04). After symptomatic treatment, the improvement of symptoms was noted in 52.5% of cases. Worsening of symptoms was noted in 42.5% leading to dose reduction in 76% of cases with secondary improvement in 63% of cases. Monitoring by the WHO sheet had made it possible to avoid changing or stopping the therapeutic line in ¿ of the cases. Indeed, a change of line was necessary in 8.6% and a permanent stop in 18.6%.