Computed tomographic (CT) scans were obtained for eleven patients with acute disseminated encephalomyelitis (ADE). Four patients had normal CT scans despite repeated examination. Abnormalities were found in seven patients and included cortical-enhancing lesions, low-density lesions in the deep white matter and basal ganglia, and edema of the brainstem. These findings support the hypothesis that both vascular injury and demyelination are involved in the pathogenesis of ADE. A delay between the onset of clinical signs and the appearance of lesions on CT scan was common. Clinical improvement was accompanied by improvement in CT abnormalities. There was a limited correlation between the clinical course and the anatomical distribution and type of abnormality seen on CT scan.