A follow-up study was performed in 42 premature infants in whom serial neonatal ultrasound and a single neonatal MRI of the brain was normal, or showed mild periventricular white matter changes. The aim of the study was to evaluate the clinical significance of periventricular signal intensity changes on MRI and to compare the predictive value of neonatal MRI with that of ultrasound. The infants underwent repeated standardised motor assessments and developmental tests. MRI was repeated at the corrected age of 12 months. Pronounced periventricular signal intensity changes on neonatal MRI and periventricular echodensities (flaring) on ultrasound were associated with a high incidence of transient motor problems during infancy. The degree of echogenicity carried the highest predictive value, as compared to duration of flaring on ultrasound and degree of periventricular signal intensity change on MRI. It is concluded that signal intensity changes on neonatal MRI represent the same ischaemic change of the periventricular white matter as flaring on ultrasound and that routine neonatal MRI screening is not warranted in premature infants without clinical evidence of neurological problems and with normal or mildly abnormal ultrasound scans. Recording of the degree of echogenicity should become a routine procedure in neonatal cerebral ultrasonography.