We report a case of Churg-Strauss syndrome (CSS) presenting as a massive pleural effusion. A 52-year-old asthmatic Japanese woman presented with progressive dyspnea caused by an eosinophilic pleural effusion (EPE). She also had chronic sinusitis, skin lesions and blood eosinophilia, but no antineutrophil cytoplasmic antibodies. Skin biopsy and the late onset of mononeuritis multiplex led to the diagnosis of CSS. The pleural effusion resolved soon after corticosteroid treatment was started. CSS is rare as a cause of EPE, but should be included in the differential diagnosis of EPE in asthmatic patients. This is the first report showing that EPE can precede other vasculitic symptoms in CSS.