During an 18-month period, 18 patients were admitted to the Beth Israel Hospital because of fecal impaction or its complications. The records of the 18 patients were reviewed to determine the presenting signs and symptoms, radiologic findings, course and etiology of fecal impaction. Prior use of drugs that slow gastrointestinal motility was found in seven cases, and seven of the 18 patients had severe neuropsychiatric illness. The presenting signs and symptoms in almost all instances were consistent with a diagnosis of intestinal obstruction. The difficulty in differentiating intestinal obstruction caused by fecal impaction from obstruction resulting from other lesions is discussed. The diagnosis of fecal impaction should be entertained only after other causes of intestinal obstruction have been excluded.