The authors studied the association of markers of inflammation with the later development of Parkinson disease (PD) using a case-control design (196 cases and 196 matched controls). The frequency of diseases of immediate-type hypersensitivity was significantly higher in cases than controls. In addition, cases used anti-inflammatory agents less frequently than controls (nonsignificant trend). The results may support the hypothesis that there is an inflammatory component in the pathogenesis of PD.