Computed axial tomography has come to be a most useful procedure in the selection, diagnosis, treatment, and follow-up of patients with inflammatory and parasitic lesions of the brain, because it allows a more accurate localization and definition of the histologic nature of lesions. Conventional contrast X-ray studies are not to be abandoned, but they do present a certain risk and do not provide the same degree of accuracy as CAT. Cerebral angiography will have to be carried out when CAT shows pathologic lesions.