We studied benzodiazepine receptors in brains obtained at autopsy from 7 normal controls and 7 patients with Alzheimer-type dementia, using 3H-flunitrazepam as a ligand. Compared with controls, 3H-flunitrazepam binding sites were significantly reduced in number in frontal and temporal cortex and hippocampus in the Alzheimer-type dementia brains. These results suggest that there are significant changes in the number of benzodiazepine receptors in selected brain regions of patients with Alzheimer-type dementia.