OBJECTIVE To determine whether human milk accelerates the recovery rate of injured small intestinal mucosa. METHODS Randomized, controlled trial. METHODS County and nonprofit, private urban hospitals. METHODS Moderately to severely malnourished infants less than 6 months of age who required parenteral nutrition for treatment of protracted diarrhea. METHODS Either a human milk preparation (n = 7) or sterile water (n = 9) was administered by continuous nasogastric feeding (14 mL/kg/d) over a 2-week study period while the infants received parenteral nutrition. RESULTS Small intestine perfusion studies and biopsies were performed at the beginning and end of the study. Age, duration of prior illness, severity of malnutrition, glucose and water absorption, disaccharidase activities, atrophy of villi, and nutritional intake were comparable in both groups of infants. At the end of the 2-week study, improvement toward normal sucrase activity and intraepithelial lymphocytes was found in significantly fewer infants in the milk group than in the water group. No differences were noted in glucose and water absorption or in lactase and maltase activities as a function of the milk versus water treatment. CONCLUSIONS Human milk did not accelerate functional recovery of the small intestinal mucosa.