In 1904 and 1905, respectively, William Campbell Posey and William Spiller both described the case of a patient with progressive ophthalmoparesis and imbalance that has come to be regarded as the earliest report of progressive supranuclear palsy. No autopsy was thought to have been performed on this patient. In this report, we review the clinical history provided by Posey and Spiller. We also report on the subsequent autopsy of their patient, which was performed by Spiller in 1906. The chief finding was a tumor involving the right cerebral peduncle and periaqueductal area. The autopsy findings prove conclusively that the patient described by Spiller and Posey had a midbrain neoplasm and not progressive supranuclear palsy.