801 patients with colon and rectal cancer were studied to assess the behavior of this cancer in the patient under 40 years of age as contrasted to the more commonly seen older patient. The younger patient had a greater frequency of advanced signs, later stages of cancer and mucoid carcinoma. However, when compared by clinical staging, the younger patient did as well or better than his older counterpart. Clinical staging was the most important prognostic factor irrespective of age. No inherent difference was found in the virulence of the cancer in the young, as the five-year survival in the younger patient (31 percent) was essentially the same as in the older patient (32 percent).