INTRODUCTION: Irritant gases and aerosols are capable of inducing acute, irritant lung injury. Lung injury caused by the inhaling nitrogen dioxide (NO2) has been known as silo-filler's disease in western countries. In Korea, acute pulmonary edema after NO2 inhalation in an industrial environment has been reported. We report here on a case of bronchiolitis obliterans after inhalation of NO2. CASE REPORT: A 54-year-old male was admitted to the hospital with dyspnea and fever. Three weeks perviously, he was diagnosed with acute pulmonary edema after occupational exposure of NO2 and he was treated with corticosteroid for 2 weeks. After cessation of the corticosteroid, he developed dyspnea and fever. High resolution computed tomography (HRCT) showed ill-defined centrilobular nodules and patterns of mosaic perfusion; this all suggested air-trapping due to bronchiolitis obliterans. We diagnosed the patient as having bronchiolitis obliterans after acute pulmonary edema due to NO2 inhalation. The corticosteroid treatment was restarted and continued for 8 weeks. CONCLUSION: NO2 induced lung injuries have variable clinical features. Close observation is needed for 6 to 8 weeks because recurrence with bronchiolitis obliterans may be seen several weeks later.