Neuropathological features of a case of ataxia-telangiectasia are reported. The main findings were the presence of Lewy bodies, cytoplasmic inclusions and axonal spheroids in the brainstem nuclei; pathological changes of spinal cord closely resembled those reported in the familial form of amyotrophic lateral sclerosis. In immunocytochemical studies, filamentous inclusions and axonal spheroids strongly reacted with monoclonal antibodies against neurofilament subunits. The results show that disorganization and accumulation of neurofilament proteins occur in ataxia-telangiectasia.