A prospective study was undertaken to determine the incidence of upper gastrointestinal disease in 85 chronic renal failure (CRF) patients on hemodialysis. Upper gastrointestinal x-rays were obtained for 83 patients, and enlarged gastric and duodenal folds were seen in 12% (10/83) and 42% (35/83) of the cases, respectively. Panendoscopy performed on 60 persons revealed gastritis in 22% (13/60), nodular duodenitis in 60% (35/60), and esophagitis in 13% (8/60). No peptic ulcers were identified either radiologically or endoscopically. Pathologic examination of mucosal biopsy specimens demonstrated gastritis in 46% (21/46) and duodenitis in 43% (22/51) of patients. A highly significant correlation was found between endoscopic and radiologic duodenitis (P less than .0001) and also between endoscopic and pathologic duodenitis. We have demonstrated a high incidence of mucosal inflammation but not ulcer disease in CRF patients. These lesions may predispose these individuals to gastrointestinal bleeding following renal transplantation.