This report concerns a case of sporadic amyotrophic lateral sclerosis (ALS) with dementia and Lewy body-like hyaline inclusions (LBHIs). The patient was a 70-year-old woman who initially showed memory disturbance and later developed bulbar palsy, muscle atrophy and weakness. The total clinical course was 51 months. The postmortem examination revealed superficial sponginess and subcortical gliosis in the frontotemporal cortices. Ubiquitin-positive intraneuronal inclusions were found in small cortical neurons of the frontotemporal lobe. Neuronal loss was marked in the spinal anterior horn with degeneration of the pyramidal tracts. The anterior horn cells had ubiquitin-immunoreactive skein-like inclusions and Bunina bodies. LBHIs were present in the lumbar horn; ultrastructurally they were composed of randomly arranged thick filamentous structures studded with granules. The LBHIs were intensely stained with anti-ubiquitin antibody. As in familial ALS and in certain cases of sporadic ALS, some of these inclusions reacted with an antibody against Cu/Zn superoxide dismutase, the enzyme whose gene was recently found to be mutated in some forms of familial ALS.