Activated microglia play a major role in the pathogenesis in neurological disorders. The transition of microglia from the normal resting state to the activated state is associated with an increased expression of receptors known as peripheral benzodiazepine binding sites, which are abundant on cells of mononuclear phagocyte lineage. PK11195 is a ligand which binds selectively to peripheral benzodiazepine binding sites, a type of receptor selectively expressed by activated microglia in the central nervous system. The ¹¹C-(R)-PK11195 positron emission tomography (PET) is already applied to many kinds of neurological disorders, including neurodegenerative disorders, and can demonstrate the role of neuroinflammation in the pathogenesis of neurological disorders. And this imaging modality also provides a means to monitor potential clinical relevance of antiinflammatory treatment strategies in vivo. This article reviews some of the clinical applications of ¹¹C-(R)-PK11195 PET in the field of movement disorders.