Sequential computerized tomography (CT) was performed on a patient with seizures and an organic mental syndrome. Cerebral sarcoidosis was subsequently diagnosed on the basis of noncaseating granulomas in three organ systems. Cranial nerve palsies, hypothalamic dysfunction, and widespread disease were absent. An unusual neuroradiologic sequence of events indicated focal and asymmetric hydrocephalus, mass effect, ependymitis, diffuse breakdown of the blood-brain barrier, and periventricular white matter destruction. These findings have not been previously described together in a patient with sarcoid. With the advent of noninvasive CT, it is possible to perform serial investigations of encephalopathies of obscure origin. Findings similar to those in the present case should prompt a thorough search for subclinical systemic involvement by sarcoid.