The inhalation of nonradioactive xenon, an inert gas that diffuses freely across the blood-brain barrier, resulted in brain enhancement which was quantitated and visualized by computed tomography (CT). Serial CT scans obtained during the buildup and equilibrium phase of xenon inhalation were used in a numerical and visual analysis of xenon accumulation in multiple selected gray- and white-matter regions in 12 patients. The calculated brain-blood partition coefficient (lambda) in normal gray matter was 0.92 +/- 0.11 and in normal white matter, 1.38 +/- 0.14. Asymmetries and delays in xenon enhancement were often visually apparent. The estimated partition coefficient was diminished more with cerebral infarction, intracerebral hematoma, and vasogenic edema than with hypoxic encephalopathy or glioblastoma multiforme. An increase in the rate of xenon accumulation was apparent by visual inspection of the motor cortex contralateral to complex hand movements. Technical factors and potential difficulties in conducting xenon-enhanced CT studies are discussed.