A 62-year-old man was referred to our department because of exertional dyspnea and a 6-year history of coughing and sputum production. He had never smoked, and had had an operation for chronic paranasal sinusitis. Coarse crackles and rhonchi were audible over both lower lung fields. The cold hemagglutinin titers were high. pulmonary function tests showed airflow obstruction, and a sputum culture revealed Hemophilus influenzae A chest X-ray film and a CT scan showed diffuse micronodular shadows in the centrilobular regions, mild ectasis of bronchioles mainly in the lower lung fields, and mild hyperinflation. A specimen of lung tissue was obtained by thoracoscopic biopsy, and histologic examination showed bronchiolitis obliterans, with bronchiolar narrowing or obliteration due to submucosal fibrosis and inflammation. Rheumatoid arthritis was diagnosed 14 months after the operation. The patient was treated with clarithromycin for 3 years. Respiratory symptoms were relieved and pulmonary function gradually improved.