This review provides an update on progressive supranuclear palsy (PSP, or Steele-Richardson-Olszewski disease), an adult-onset neurodegenerative disorder characterised by early postural instability, which leads to falls, and a vertical supranuclear-gaze palsy. Recent epidemiological studies have shown that the disorder is more common than previously recognised, that it is commonly misdiagnosed, and that it may present to a wide range of hospital specialists. The diagnosis of PSP hinges on clinical acumen. Attempts to identify a suitable biomarker in the CSF or a specific and sensitive imaging or neurophysiological technique have so far failed to have a significant effect on the diagnostic process. Better understanding of the molecular pathology of PSP has highlighted the importance of tau-protein accumulation and tau-genotype susceptibility in its pathogenesis. No drug treatment significantly and consistently benefits patients, and novel therapies are urgently required.