Twenty-seven cases of chronic intestinal pseudo-obstruction are reported. The causes of pseudo-obstruction were progressive systemic sclerosis in 14, hollow visceral myopathy in 4, visceral neuropathy in 2, sclerosing mesenteritis in 1, and jejunal diverticulosis in 1. No identifiable cause was found in five. Chronic pseudo-obstruction is a long-term illness characterized by vomiting, abdominal distention, abdominal pain and weight loss. Involvement is often present throughout the intestine so that patients may present with a variety of symptoms deriving from the esophagus, stomach, small intestine, and colon. Hollow visceral myopathy and visceral neuropathy are usually familial and urologic involvement is sometimes present in the former. Abnormalities of smooth muscle function can be discerned by radiography and esophageal manometry. The pattern and distribution of the abnormalities are helpful in differentiating pseudo-obstruction from true mechanical obstruction. They may also be helpful in differentiating one form of pseudo-obstruction from another. The majority of cases have identifiable pathology within either the smooth muscle or myenteric plexus of the bowel wall. The natural history of pseudo-obstruction is variable. Remissions and exacerbations occur and may be unrelated to anything that is done therapeutically. The illness is unresponsive to any drug known to have an effect on intestinal motility. Antibiotic treatment of small intestinal bacterial overgrowth and selected surgical procedures may occasionally be palliative. Many patients develop malnutrition and require home parenteral nutrition in order to survive.