Twenty-five of the initial computerized tomographic (CT) scans of 63 neonates had "definite" abnormalities. These abnormalities included dilated ventricles, advanced hypodensities extending beyond the periventricular areas, and varieties of hemorrhage. Thirty-six, with otherwise normal intracranial structures, were found to have localized periventricular frontal or frontooccipital areas of low attenuation. These areas were confined to the white matter of the periventricular area and have been identified by others as indicating "periventricular leukomalacia." In follow-up clinical studies on 26 of this latter groups, only two showed neurological abnormalities. Seven CT scans were repeated; only one was abnormal. In this case, the attenuations had disappeared, but were replaced by mild deep and cortical atrophy. The patient then showed findings suggesting a mild spastic diparesis and psychomotor delay. Our findings suggest that periventricular low attenuations in an otherwise normal CT scan are usually due to incomplete myelination or, at least, a transient abnormality. Periventricular low attenuation cannot be used as a diagnostic sign of periventricular leukomalacia, nor does it necessarily suggest an unfavorable prognosis.