Background: Human milk is the optimal food for newborns. Choices to feed preterm infants in neonatal intensive care units are mother's milk, donor milk, or formula. Preterm infants have better tolerance for human milk, but the lower caloric density of donor milk might not meet preterm infant growth needs. Preterm infants have higher protein and energy requirements with a limited stomach capacity. Therefore, there is a need for human milk with increased nutrient density. Research Aim: To concentrate donor milk to have a higher caloric and protein density while avoiding side effects of high osmolality by precipitating lactose at low temperatures. Methods: We investigated the results of volume reduction and lactose removal processes on the lactose, protein, osmolality, and viscosity of human milk. Donor milk was obtained from WakeMed Mothers' Milk Bank. Homogenization and evaporative condensation were applied to samples (N = 36) before they were stored frozen overnight, followed by refrigerated centrifugation for lactose removal at 0 degrees C. Supernatants were separated and compared to the composition of controls. Results: A significant reduction of lactose (S-W = -262, p < .0001) and osmolality (S-W = -211.5 p < .01) was achieved in the concentrated milk without a significant protein loss from centrifugation (S-W = -44.5, p = .49). A 30%-40% volume reduction is within the American Academy of Pediatrics recommended osmolality for infant feeding. Conclusion: Concentrating human milk in a milk bank setting for feeding preterm infants might be a simple and low-cost process to achieve a product with higher nutrient density and no non-human components.