Donor human milk has emerged as the preferred substrate to feed extremely preterm infants, when mother's own milk is unavailable. This article summarizes the clinical data demonstrating the safety, efficacy, and cost-effectiveness of feeding donor human milk to premature babies. It describes the current state of milk banking in North America, as well as other parts of the world, and the differing criteria for donor selection, current pasteurization techniques, and quality control measures. A risk assessment methodology is proposed, which would allow milk banks globally to assess the safety of their process and respond appropriately to differing risk environments.