More than 45,000 of 100,000 exposed patients are suffering from late effects of sulfur mustard (SM) after almost 20 years post-exposure. Respiratory complications of SM exacerbate over time and are the greatest cause of long-term disability in exposed patients. A triad of cough, expectoration and dyspnea has been found to be the main symptoms among patients. Even those who had not developed acute symptoms may suffer from late respiratory complications. Pulmonary function test studies have revealed more obstructive patterns than restriction. High-resolution computed tomography (HRCT) is supposed to be the diagnostic imaging tool of choice in patients with history of SM exposure while chest x-ray may not be helpful. In contrary to earlier reports of interstitial pulmonary fibrosis in these patients, HRCT and pathological studies revealed the diagnosis of bronchiolitis obliterans. Bronchodilators and corticosteroids are widely used to resolve respiratory symptoms of mustard lung. Macrolides and antioxidants may improve respiratory symptoms and pulmonary function. Interferon gamma could improve pulmonary function of SM exposed patients with bronchiolitis.