Fifty neonatal and infant heads were examined using a 5 MHz real-time sector scanner. Anatomic detail superior to that previously described was achieved by this method. Normal structures routinely imaged included the entire ventricular system and many parts of the subarachnoid spaces. The gray scale detail of parenchymal structures was usefully demonstrated. Routinely visualized vascular structures included the anterior cerebral artery system, the middle cerebral arteries, the choroid plexus, and the posterior cerebral arteries. Hydrocephalus, as well as intraventricular hemorrhage and its sequelae, were investigated. Computed tomography (CT) is considered diagnostic in hydrocephalus and intraventricular hemorrhage, but evaluation by sonography compares favorably. Among other advantages of sonography are the feasibility of bedside scans without removing the patient from the intensive care nursery and the elimination of ionizing radiation.