We have performed serial trans-fontanelle sonography on 69 newborns with perinatal asphyxia. Ten neonates presented high ultrasonic density in the thalamus and the basal ganglia. These images were preceded, in eight of them, by diffuse echoes for all of the CNS, corresponding to cerebral edema. The most significant clinical findings were convulsions and important depression of conscience level and muscular tone. Eight of ten newborns presented major abnormalities in the electroencephalogram (severe depression of background). Since its coexistence with other parenchymal lesions and poor neurologic development, we consider the ganglio-thalamic ultrasonic densities to be a sign of severe ischemic hypoxic cerebral damage.