A 70-year-old male with the Cronkhite-Canada syndrome died from unrelated causes, 18 months after the onset of symptoms. Although generalized malabsorption and exudative enteropathy were present, the predominant clinical feature was high fecal water and electrolyte loss. The latter was primarily caused by a combination of acquired disaccharidase deficiency and intestinal bacterial overgrowth leading to excessive ileal and colonic carbohydrate fermentation. Low levels of circulating IgM and impairment of delayed hypersensitivity were observed. The basic alimentary tract lesion was a diffuse, potentially reversible, gastroenterocolitis associated with formation of inflamma- tory pseudopolyps.