Myelination of the central nervous system (CNS) can be demonstrated with magnetic resonance (MR) imaging. Myelin formation may be reduced in conditions of neonatal "undernutrition". Very preterm infants have a reduced postnatal growth rate when compared with intrauterine fetuses of the same gestational age. Using MR imaging, we studied qualitative myelination patterns in healthy preterm infants of less than 30 weeks gestation with an optimal nutritional intake and in term infants at 44 weeks postmenstrual age (PMA). At that age, preterm infants had a significantly lower mean body weight than term infants, but mean head circumference did not differ significantly. All preterm and term infants had reached myelination stage M3 (myelin in brainstem, internal capsule, and corona radiata) and M4 (myelin in brainstem, internal capsule, corona radiata, and centrum semiovale). There was no significant difference in myelination stage between the preterm and term infants. We conclude that adequate nutrition in the neonatal period leads to qualitatively adequate myelination of the CNS in very preterm infants.