Pathological changes of the superior cerebellar peduncle (SCP) can occur in PSP. We assessed the clinical history and signal changes in the SCP on fluid-attenuated inversion recovery (FLAIR) images of 12 patients with clinically probable PSP. Three control groups were studied: Parkinson's disease (PD), multiple system atrophy with predominant parkinsonian features (MSA-P), and healthy controls. Three patients who had clinically probable PSP showed increased FLAIR signals within the SCP. No subject with PD or MSA-P showed any signal changes of the SCP. The signal changes in the SCP on FLAIR may be one indicator for differentiating PSP from other parkinsonian diseases.