Respiratory bronchiolitis-associated interstitial lung disease has been described among current or former smokers and has features consistent with interstitial lung disease. Symptoms include cough, dyspnea on exertion. Lung pathology is characterized by the accumulation of pigmented macrophages within respiratory bronchioles and adjacent air spaces associated with mild thickening of the peribronchiolar interstitium. It must be separated from the other interstitial lung disease because of marked differences in treatment and prognosis. Recently we experienced a case of respiratory bronchiolitis -associated interstitial lung disease in a 48-year-old man. As far as we know, this is the first case in Korea.