We report clinical and computed tomography (CT) findings in 17 patients with progressive supranuclear palsy (PSP). Patients were divided into four clinical groups according to the severity of the disease and functional disability. In Grade 1, patients demonstrated minor disability and decreased anteroposterior (AP) diameter of the midbrain tegmentum was present. As the disease progressed clinically to Grade 2, more severe atrophy of the pons and midbrain and dilatation of the quadrigeminal plate cistern were noted. The most severe stages of clinical disability (Grades 3 and 4) were characterized radiologically by dilatation of the aqueduct, progressive dilatation of the third and fourth ventricles and atrophy of the temporal lobes. Cortical atrophy was variable and not a prominent radiological feature. Midbrain and pontine AP diameters were significantly smaller in PSP patients than normal patients. Serial studies showed progressive involution of the pons and midbrain and enlargement of the third ventricle. While the most obvious CT changes in PSP occur late in the disease, CT may in fact suggest the correct diagnosis long before the classic clinical picture is evident.