We report the autopsy findings of an 82-year-old woman who exhibited slowly progressive upper motor neuron signs (pseudobulbar palsy, muscle weakness and positive Babinski's sign) in the absence of lower motor neuron signs, which were followed by progressive dementia and frontotemporal atrophy, and who died 7 years and 4 months after onset of the disease. In this patient, the upper motor neuron system, including the precentral cortex and descending pyramidal tract, was severely degenerated, but the lower motor neurons and innervated skeletal muscles were well preserved. A few lower motor neurons were found to contain cytoplasmic inclusion bodies characteristic of amyotrophic lateral sclerosis (i.e., Bunina bodies and ubiquitin-positive skeins). However, fragmentation of the Golgi apparatus was not evident in the anterior horn cells examined. Therefore, it was considered that the lower motor neurons were also involved, but that the rate of degeneration of these neurons was very slow in the disease process. Marked frontotemporal lobar degeneration characterized by microvacuolation, and ubiquitin-positive neuronal inclusions and dystrophic neurites in cortical layer II were also observed, the precentral cortex being the most severely affected area. Similar ubiquitin-positive structures were also observed in the neostriatum. Finally, a survey of the literature based on this patient's clinical and pathological features led us to conclude that the rare clinical syndrome of primary lateral sclerosis is, in general, a rare upper-motor-predominant form of amyotrophic lateral sclerosis that is often accompanied by frontotemporal lobar degeneration with ubiquitinated neuronal inclusions.