Although considerable research effort has been expanded to improve the drug treatment of colorectal cancer, progress has been slow. 5-fluorouracil (5-FU) is still the agent of choice and no other drug or combination of drugs has been found superior. When combined with radiation therapy 5-FU is superior to irradiation alone in the treatment of localized carcinoma of the rectum. When used as an adjuvant in the management of patients with a poor prognosis after definitive surgical resection, 5-FU has not improved survival or delayed the time to recurrence. Further controlled trials are modalities of therapy to improve these results.