We studied 104 patients with progressive supranuclear palsy (PSP), 38 of whom were examined by both a neurologist and a neuro-ophthalmologist. Neuro-ophthalmic findings that may help differentiate PSP from Parkinson's disease include vertical supranuclear ophthalmoparesis and fixation instability. Eyelid abnormalities, particularly lid retraction, blepharospasm, and "apraxia" of eyelid opening and closure, were important distinguishing signs. Although downgaze palsy is felt to be the clinical hallmark of PSP, upgaze and downgaze were equally affected at the time of diagnosis in our patients.