A 51-year-old Japanese man with Churg-Strauss Syndrome (CSS) diagnosed by pleural biopsy is described. He was hospitalized because of high fever and bilateral knee, elbow and shoulder joint pain. Chest roentgenogram and chest computed tomography (CT) scan revealed bilateral massive pleural effusion. Pleural biopsy revealed eosinophilic infiltration and necrotizing granulomas. He was treated with oral prednisolone and his symptoms improved. This is the first report of CSS diagnosed by pleural biopsy.