Obliterant Bronchiolitis is an anatomo-clinical entity known years ago. It is recognized as a evolutive form of different processes, including Extrinsic Allergic Alveolitis, Pneumonitis due to gas inhalation, viral processes and Rheumatoid Lung. It has been recently identified as a disease with specific characteristics in the context of interstitial idiopathic pneumonia with bronchiolar involvement and a distinctive anatomo-pathological character. From the clinical and radiological point of view it requires a broad differential diagnosis, which is confirmed definitively in the anatomopathological exam obtained through minithoracotomy. Therapeutic response to corticosteroids is good even thought it shows a trend to relapse when they are decreased or stopped. We discuss the cases of three patients who were studied recently, showing their clinical, radiological and anatomopathological features together with the therapeutic response, which is positive, in different periods of the evolution course.