Abstract A man, aged 72 years, who came to hospital with a 9-month history of increasing constipation, had a narrowed segment of sigmoid colon removed. Increased numbers of nerve fibres and ganglion cells were found histologically in the plexuses of Auerbach and Meissner, and in the muscular layers of the affected bowel. This is apparently the first recorded case of this type of ganglioneuromatosis of the pelvic colon. The lesion was radiologically indistinguishable from a stenosing carcinoma of the colon.