Renal failure is said to be a risk factor for peptic ulceration, although most previous studies were small and utilized radiology rather than endoscopy for diagnosis. We endoscoped 114 of 126 patients with end-stage renal failure on maintenance hemodialysis and found peptic ulcer in two (2%); one other patient not endoscoped had previously undergone ulcer surgery. Erythema, petechial spots, or erosions were found in another 58 patients (51%). The ranges of gastric acid output and serum gastrin were wide and were inversely correlated. The prevalence of peptic ulcer among patients on hemodialysis therefore appeared to be no higher than that in the general population. Elevated serum gastrin levels may be a response to hypochlorhydria.