The neuropathologic findings in a 31 year old patient with ataxia-telangiectasia are presented. There was an unusually severe and widespread distribution of the recognized abnormalities within the nervous system. In addition, there were Lewy bodies in the substantia nigra and widely distributed vascular changes in cerebral tissue. The nature of the vascular changes is discussed. These findings underline and expand the known spectrum of nervous system involvement in this condition.