&NA;Colonic malignancy in the first two decades of life is relatively rare. Its poor prognosis is probably due to the biologic differences relative to cell type and the aggressive nature of these neoplasms, and to the often long delay in diagnosis as clinicians sometimes fail to realize that this problem can occur in young persons. A two‐or three‐week history of abdominal pain in a child should therefore be investigated as it would be in an adult. If a large‐bowel tumor is found, appropriate radical surgery should be performed, except in cases of lymphomas of the rectum and rectosigmoid, where radiotherapy is preferred. Also, scrutiny of family members of these young patients with rectal and colonic cancers is advocated.