Objective: To determine the frequency of Lewy bodies (LB) in progressive supranuclear palsy (PSP). Background: LB are characteristic of PD, but are also found in normal controls and in other neurodegenerative diseases, especially AD. Methods: The authors evaluated the brains of 72 consecutive cases of pathologically confirmed PSP and 98 normal controls, ranging in age from 60 to 100 years, with immunohistochemistry for alpha -synuclein. Results: LB and Lewy neurites were found in 13 cases of PSP, with the most numerous LB and Lewy neurites in the basal forebrain and amygdala; most cases also had LB in the substantia nigra. The frequency of LB in the substantia nigra (12%) was comparable to the frequency of LB in controls (9%). Conclusions: In contrast to increased frequency of LB in AD, there is no apparent interaction between LB and the tau pathology in PSP.