Metabolic bone disease (MBD) in the newborn predominantly affects preterm infants. The risk of MBD is inversely proportional to gestational age and birthweight, and directly related to postnatal complications. Poor bone mineralization has been shown in 55% of infants born at less than 1000 g. Optimal nutrition for very preterm infants is thought to be mother's own milk but supplementation is required to meet dietary requirements. However, there is insufficient evidence to determine that supplementation of human milk with commercial fortifiers has an effect on bone mineral content. We report a case of severe MBD with fractures in an extremely preterm infant who was fed with fortified mother's milk.