Alzheimer-type dementia (ATD) was discussed not only from the aspects of forensic neuropathology by using various techniques for general stains and silver-impregnation, but also immunohistochemically by using antiserum against glial fibrillary acidic protein which is a specific marker for astrocytes. There were marked differences in microscopic findings of ATD group and control group of elderly subjects whose intellectual have been maintained. The main histological features of ATD were presence of numerous senile plaques and neurofibrillary changes, and both of them were thought to be helpful diagnosis markers. Double stains by glial fibrillary acidic protein (GFAP) stain using avidin-biotin peroxidase complex (ABC) method and Congo red stain were performed. By the former stain, typical senile plaques, encircled by reactive astrocytes and penetrated interior by their processes, were demonstrated. By the latter stain, amyloid core was well detected. Another method which is particularly sensitive to amyloid, such as amyloid core or amyloid angiopathy, is the thioflavin S stain. Immunohistochemical stains for glial fibrillary acidic protein demonstrated an intense participation within the plaques by processes of reactive astrocytes. Using the autopsy criteria for the diagnosis of Alzheimer's disease reported by Khachaturian, senile plaques were counted on microscopic magnification x200 field. Numerous plaques satisfying thoroughly the criteria were detected. The report by Blessed et al. that there is a highly significant correlation between mean plaque counts in sections of cerebral cortex of elderly subjects and degrees of dementia is very helpful for forensic pathologists and is highly evaluated.