The elemental content of neurons of the hippocampus was studied by a combination of scanning electron microscopy and x-ray spectrometry in autopsy-derived brain tissue from three cases of senile dementia (Alzheimer type) and three nondemented elderly controls. Foci of aluminum were detected within the nuclear region of a high percentage of neurons containing neurofibrillary tangles from the cases of senile dementia as well as the elderly controls. The adjacent normal-appearing neurons from both groups of patients were virtually free of detectable aluminum. These findings suggest that the association of aluminum to Alzheimer's disease extends to the neuronal level.