Bronchiolitis obliterans with organizing pneumonia (BOOP) is a nonspecific form of pulmonary injury related to different etiologic agents. The disorder is not only limited to the alveoli but also affects to the alveolar ducts and distal bronchioles. This fact may differentiate this disorder of others with chronic inflammatory diffuse alveolar lesion as chronic eosinophilic pneumonia (CEP), extrinsic allergic alveolitis (EAA) or diffuse alveolar damage (DAD). It has been described an idiopathic form and other associated with connective tissue diseases, infections, organ's transplantation, drug or chemical induced reactions, irradiation pneumonitis and aspiration pneumonitis, among others. Their extremely variable clinical presentation and course, etiology, and histologic appearance and, in some way, the considerable confusion as a result to the different terminologies applied, has made difficult a clear understanding of this disease. We present two cases of BOOP related to infection by measles virus, whose diagnostic was obtained through pulmonary thoracoscopic biopsy and serological study respectively. Patients were treated with steroids (6 months) with a favorable outcome in terms of clinical symptoms, radiological findings, and a normalization of the pulmonary function tests. We suggest that in each patient with clinic and radiological study suspicious of BOOP, it seem to be useful to include measles virus in serologic study. This investigation may contribute to reduce the number of cases classified as idiopathic BOOP.