We describe the autopsy finding in a male patient with senile dementia of unusually prolonged total duration, who had exhibited atypical neuropathologic findings. During clinical course, memory disturbance had been more prominent than deterioration of other cognitive functions. Neuropathologic examination revealed neurofibrillary changes which were prominent in the hippocampal region and scattered in the amygdala and in the predilection sites of the hypothalamus and brain stem. This distributional pattern was that in Alzheimer-type dementia. The most characteristic finding was scanty senile plaques, which were scattered predominantly in the basal and medial portion of the frontal lobe. Although the clinical course and pathological findings of this case were in slight degree and deviated from those in usual senile dementia, it is thought that the entity in this case was dementia of the Alzheimer-type.