Histopathologic features of duodenal and jejunal mucosal biopsy specimens obtained from 58 patients with portal hypertension and 30 healthy volunteers were studied. Dilated mucosal vessels with thickened walls were seen in duodenal and jejunal biopsy specimens from 39 (67%) and 41 (71%) of the patients, respectively, compared with corresponding biopsy specimens from 8 (27%) and 6 (2%) of the control subjects. The difference between the two groups was statistically significant. Other important histologic features in the patient group included edema of the lamina propria, fibromuscular proliferation, a decreased villous/crypt ratio, and thickened muscularis mucosae. The mean +/- SD thickness of capillary wall and diameter were significantly more in the patient group compared with those in the control subjects. We conclude that thick-walled dilated vessels along with edema of the lamina propria, fibromuscular proliferation, a decreased villous/crypt ratio, and thickened muscularis mucosae form a characteristic picture of portal hypertensive enteropathy. These changes seem to be a part of the changes seen in the gastrointestinal tract of patients with portal hypertension without any meaningful clinical implication except the increased chance of occult gastrointestinal blood loss.