Individuals with chronic renal failure (CRF) may have a variety of gastrointestinal (GI) problems, including dyspepsia, acid peptic disease, and bacterial overgrowth. We investigated gastrointestinal function in 11 uremic patients, seven of whom were on dialysis three times a week and four who were not on dialysis. Ten normal subjects were studied as controls. The nutritional status of the patients did not differ from that of the control subjects. Seven patients demonstrated abnormal GI endoscopic findings, although none was severe; they also had prolonged oral-cecal transit times but had no evidence of bacterial overgrowth, and all had normal numbers of lymphocyte subpopulations within the intestinal mucosa. The patients had significantly reduced activities of mucosal sucrase and maltase but not of lactase. In spite of the reductions in these enzymatic activities, carbohydrate malabsorption was not evident in the CRF group, probably because of the vast reserve of the small intestine. No differences were noted between the groups in the activities of several intestinal peptidases. From these data, we concluded that GI function is essentially normal in patients with CRF and postulate that this normality, which is in contrast to previous findings, is related to recent advances in the clinical management of uremic patients.