The beneficial effects of human milk extend to the feeding of premature infants, because their nutrition support must be designed to compensate for metabolic and gastrointestinal immaturity, immunologic compromise, and maternal psychosocial conditions. Significant effects on the recipient host, such as reduction in sepsis and necrotizing enterocolitis, have been reported for premature infants fed their mothers’ milk. However, nutritional concerns arise because the quantity of nutrients in breast milk may not meet the great nutrient needs of premature infants born weighing <1500 g. Human milk supplements, or fortifiers, are available to augment the nutrient content of unfortified breast milk. Host defense benefits observed in infants fed unfortified human milk also are found in premature infants fed fortified human milk. Availability of milk is an issue for mothers delivering prematurely. Donor pasteurized human milk has been suggested as a proxy for the mother's own milk. Am J Clin Nutr 2007;85(suppl):625S-8S.