To demonstrate a relationship between diarrheal incidence and the onset of hypoalbuminemia developing as a result of acute protein-calorie malnutrition and severe catabolism, we initially studied two patients who had developed severe hypoalbuminemia (less than 2.5 g/dl) and diarrhea on a variety of enteral diets. Each patient was placed on a peptide enteral formula at a rate of infusion equivalent to that used during the previous 24 h. Diarrheal volumes decreased significantly from greater than 1500 to less than 100 ml/day and from greater than 4000 to 800 ml/day. We subsequently studied 12 patients in a randomized, prospective fashion to confirm our previous observations. Seven patients received a peptide enteral formula, and five received a standard isotonic enteral formula as a control. The patients were monitored for a minimum of 2 wk or until serum albumin levels reached 3 g/dl. Nutritional variables were measured initially and every 4 days for the duration of the study. Of the patients receiving the isotonic feeding, only one of five completed the study period without diarrhea. Two patients died unrelated to the feeding, and three patients developed severe diarrhea within 48 h of institution of the study. Of the seven patients receiving the peptide feeding, six completed the study period without diarrhea. One patient had a large stool volume initially which decreased by day 2 of the study. We conclude that a peptide enteral formula is well tolerated in patients with severe hypoalbuminemia when compared to a standard isotonic enteral formula. The ability to provide enteral nutrition in a form that is well tolerated in hypoalbuminemia patients may obviate the need for parenteral nutrition routinely in these patients.