Stercoraceous ulcers are lesions in the mucous membrane of the colon and rectum caused by pressure of inspissated or impacted fecal masses. This complication of constipation and malnutrition is limited to elderly or bed-confined patients. Penetration of the intestinal wall can occur, with subsequent peritonitis. Stercoraceous ulcers were diligently searched for during 175 nonselected autopsy examinations, because the condition has been so infrequently diagnosed either prior to or after autopsy. This search disclosed that such ulcers had occurred in 10 patients. Perforation with secondary peritonitis was the cause of death in four. Constipation had been a difficulty in six of the patients, and two others had had rectal bleeding. Gross microscopic morbid anatomy of the ulcer is characteristic enough to allow diagnosis, even though the fecal mass may not be found at autopsy.