A 60-year-old woman was admitted with low fever, dry cough and occult hematuria with abnormality on her chest X-ray film showing patchy shadows in the apices of both lungs. The patient was seronegative for PR-3 ANCA and seropositive for MPO-ANCA and transbronchial lung biopsy showed inflammatory granulation tissue. We performed an open lung biopsy to achieve a definitive diagnosis. The lung specimen showed the typical findings of Wegener's granulomatosis. Renal biopsy revealed necrotizing glomerulonephiritis. A systemic form of Wegener's granulomatosis was diagnosed. Initilal treatment combined oral prednisolone at 30 mg daily with oral cyclophosphamide at 50 mg daily improved not only the clinical course, but also the radiographic findings. Finally, she became seronegative for MPO-ANCA.