Bronchiolitis obliterans organizing pneumonia (BOOP) is an uncommon pulmonary disorder which is a clinicopathologic syndrome. The typical symptoms include cough, fever and dyspnea. Corticosteroid therapy is effective. Death from progressive disease is infrequent. We report a case of BOOP in a 41-year-old male non-smoker, proved by pathologic findings. After steroid therapy (prednisolone 30 mg daily) for 10 days, he developed spontaneous pneumothorax of bilateral lung fields. Responses to steroid and chest tube thoracostomy were excellent. BOOP may be complicated with spontaneous pneumothorax which may adversely affect prognosis. BOOP should be included in the differential diagnosis of patients presenting with secondary spontaneous pneumothorax.