A 49-year old man who had been treated for five months at a private clinic due to chronic paranasal sinusitis was admitted to our hospital because of recently aggravated nasal stuffiness, headache, and cough. The X-ray film of paranasal sinuses and facial CT scan showed marked mucosal thickening of the nasal cavity and paranasal sinuses. The plain chest film and chest CT scan showed multiple, variable sized, pulmonary nodules in both lungs. The level of c-ANCA was elevated and urinalysis revealed proteinuria and hematuria. Percutaneous lung and kidney biopsies were performed for confirmative diagnosis. Histologic examination of the lung nodule demonstrated extensive necrosis and poorly-formed granulomatous inflammation. The histologic finding of the kidney showed focal necrotizing glomerulonephritis. A diagnosis of Wegener's granulomatosis involving the paranasal sinuses, lung and kidney was made, and treatment was successfully performed with cyclophosphamide and prednisone.