Chronic constipation is a frequent symptom in patients with dementia, especially in those institutionalized. However, few data are available on the neuropathological aspects of the colon in such patients. We investigated the enteric neuropathology of the colon in two patients with longstanding dementia and intractable constipation, requiring surgery to alleviate symptoms. The results were compared to those obtained in 10 controls. No abnormalities were found at conventional histological examination, except for the presence of melanosis coli. Immunohistochemical evaluation revealed no important difference between patients and controls, except for a decreased number of enteric neurons in patients. However, this neuronal decrease was not associated to apoptotic phenomena, as observed in patients with severe idiopathic constipation. We concluded that in severely constipated patients with dementia the neuropathological abnormalities might be reconducted to a physiological neuronal decrease as a result of aging, and that the pathophysiological aspects of constipation in these subjects differ from those found in idiopathic constipation.