Cryptogenic organizing pneumonia (COP) is one of the new recognized histological patterns of idiopathic interstitial pneumonias, in witch no cause or association is identified. Idiopathic bronchiolitis obliterans-organizing pneumonia (BOOP) is a synonymous. This rare entity is characterized by involvement of alveoli and bronchioles, which are filled by intraluminal polyps of fibroblastic tissue (Masson bodies). The clinical presentation often mimics that of community-acquired pneumonia. Persistent non-productive cough, dyspnoea with exertion and weight loss are common features, and in one-half of the cases the onset is heralded by a flu-like syndrome. Definitive diagnosis depends on histological data, and video-assisted thoracoscopic (VAT) has become the established technique. Spontaneous recovery is rare; corticosteroid therapy provides cure in two thirds of cases. The authors present a case of a patient whose lung biopsy by VAT confirmed the diagnosis. She was treated with corticoids without recurrence in a two year follow-up.