A systematic ultrasonographic study and a prospective neurodevelopmental assessment were carried out in a population of high-risk neonates. In group A (82 preterm infants of 34 weeks gestation or less), periventricular-intraventricular hemorrhage (PVH) and periventricular leukomalacia (PVL) were the commonest lesions. The association of PVH, PVL and ventricular dilatation had a variable outcome and the prognosis was found to be poorer in the presence of diffuse or extensive PVL. In group B (115 neonates of more than 34 weeks gestation), miscellaneous ultrasound changes were observed (malformations, infections, hemorrhages and hypoxic-ischemic lesions). Malformations, hypoxic-ischemic damage and prenatal infections had a gloomy prognosis. The main targets of hypoxic-ischemic damage in the immature infant were the germinal layer and the periventricular white matter, while in the mature infant the cortex and basal ganglia were more vulnerable. A relation between the localization and the size of the lesion could be established. In conclusion, basic forms of cerebral damage should therefore be understood in terms of brain maturation, type and timing of the insult, extent and localization of the lesion.