Neocortical neurofibrillary tangles (NFT) revealed by Bodian technique and anti-tau immunolabelling were seen in 5/5 cases of progressive supranuclear palsy (PSP) aged 58-76 years. These lesions differed from Alzheimer's disease or age-related changes: (1) they were most frequent in the precentral gyrus (Brodmann's area 4) whereas associative areas are predominantly lesioned in Alzheimer's disease; (2) they affected mainly large pyramidal neurons and small cells, relatively sparing the cell population selectively involved in Alzheimer's disease; (3) they predominated in layers V and VI of area 4, whereas NFT are most dense in layers III and V in Alzheimer's disease; (4) mature senile plaques (1/5 cases) and beta-amyloid diffuse deposits (3/5 cases), which usually precede or go together with NFT in Alzheimer's disease were rare or absent (2/5) in PSP. Neuropil threads and tufts of abnormal fibres were also seen. In addition, NFT and neuropil threads were found in the hippocampus. PSP is thus another example of abnormal storage of tau developing in the neocortex in the absence of beta-amyloid deposits. It might prove a useful model for the understanding of the mechanisms of localization and spreading of tau storage in the brain.