OBJECTIVE- To review clinical and basic research on progressive supranuclear palsy.METHODS- MEDLINE literature review search from 1966 to 1997.CONCLUSIONS- Significant progress has occurred since Steele, Richardson, and Olzewski first described this disorder as a specific clinicopathologic entity 33 years ago. Clinical features, laboratory testing, and therapeutic strategies are discussed. In addition, hypothesized pathogenetic mechanisms that may help in the search for appropriate biologic therapies are considered.