The results of cranial ultrasonography (US) and computed tomography (CT) were compared in 52 full-term neonates and young infants. The chief indications for examination included: increasing head size, dysmorphic features, myelomeningocele, inflammatory disease, and asphyxia. Disorders detected included hydrocephalus, parenchymal abnormalities, intracranial hemorrhage, extraparenchymal fluid collections, and vascular and other developmental malformations. Hydrocephalus and subdural collections were seen in patients referred for all clinical indications, whereas diffuse parenchymal abnormalities, subarachnoid hemorrhage, and intraventricular hemorrhage occurred primarily in patients with hypoxia. CT and US essentially were equivalent in detecting hydrocephalus, moderate to large intraventricular hemorrhages or subdural collections, and large focal parenchymal lesions, although CT was somewhat better in determining the level and cause of obstruction in patients with hydrocephalus and characterizing parenchymal abnormalities. CT was more sensitive than ultrasound in detecting subarachnoid hemorrhage (100% vs. 0%), diffuse parenchymal abnormality (100% vs. 33%), and small intraventricular hemorrhages (100% vs. 0%) but these lesions often were not clinically significant. The results suggest that US should be used as the primary neuroradiological examination in term infants; CT probably should be reserved for further investigation after US in those patients with a history of hypoxia and progressive clinical deterioration.