The frequency of Alzheimer's neurofibrillary tangles was studied, employing large sections of the cerebral hemispheres, in the cerebral cortex in 2 cases of progressive supranuclear palsy. The majority of the neurofibrillary tangles were found in the smaller nerve cells of the third layer. The typical triangular form was rare, and most of them showed argyrophilic neurofibrillary filaments which coiled around the well-preserved nucleus. We concluded that their occurrence in the cerebral cortex is one of the morphological manifestations of the disease process.