We studied 43 patients with ganglioneuromas of the gastrointestinal tract accessioned at the Armed Forces Institute of Pathology (AFIP) from 1940 to 1990 in order to determine their relation to von Recklinghausen's disease and other multiple tumor syndromes. They fell into three groups: polypoid ganglioneuroma (28 patients); ganglioneuromatous polyposis (7 patients); and diffuse ganglioneuromatosis (8 patients). Follow-up (1-24 years, average 8 years) for 16 of 28 patients with polypoid ganglioneuroma showed that none of these patients developed von Recklinghausen's disease or evidence or multiple tumor syndromes. Three of seven patients with ganglioneuromatous polyposis were alive and well but were reported to have multiple cutaneous lipomas and one reported a family history of multiple intestinal polyps. For seven of eight patients, diffuse ganglioneuromatosis was associated with other tumors, namely multiple endocrine neoplasia type IIb, multiple ganglioneuromas and neurofibromas limited to the gastrointestinal tract, von Recklinghausen's disease and neurogenic sarcoma. We conclude that the solitary polypoid ganglioneuroma of the gastrointestinal tract is not associated with the subsequent development of von Recklinghausen's disease or multiple endocrine neoplasia. All three forms of gastrointestinal ganglioneuromatous disease appear to be largely centered in the colon and rectum, unlike neurofibromas and neurofibromatosis, which, in our experience, occur more commonly in the small intestine and stomach.