Galactose is a major nutrient in normal newborn infants and serves as a substrate for energy production and fuel storage and a regulator of carbohydrate assimilation. Inborn errors of galactose metabolism have contributed to our understanding of the potential toxicity of this carbohydrate. In addition to the classic acute manifestations of neonatal galactosemia, long-term follow-up of surviving patients have revealed unusual neurodevelopmental and reproductive problems. Many investigators have suggested that the newborn infant can utilize galactose better than adults and that neonatal galactose assimilation exceeds that of glucose. Galactose may be an excellent substitute for glucose among hyperinsulinemic infants of diabetic mothers or premature infants with glucose intolerance. However, until further investigations are performed to define the role of galactose in newborn nutrition and to determine its potential toxicity, galactose should not be used as the primary carbohydrate in sick newborn infants.