Behcet's disease is a chronic multisystem vasculitis of unknown aetiology, affecting many organs including skin, joint, eyes, central nervous system, gastrointestinal tract, kidneys, epididymis, heart, lung, large arteries and veins. Pulmonary involvement is rare in Behcet's disease, approaching 1-5% in different series. The main features of lung involve¬ment consist of vasculitis forming multilocular aneurysms and thrombosis of the pulmo¬nary artery. Hemoptysis is the dominant clinical feature of Behcet's pulmonary arteritis. Chest x-ray, computed tomography, angiography, pulmonary perfusion scan and bronc-hoscopy are useful foreevaluating vascular change. It is suggested that corticosteroid treatment alone or in combination with an imunosuppressive agent such as azathioprine, cyclosporin or cyclophosphamide should be considered as a first-line treatment. Anticoa-gulant treatment in the presence of hemoptysis may be hazardous and should be avoided. If there is no response to medical treatment, surgical excision of pulmonary artery aneu-rysms or local resection of the involved lung should be considered. Pulmonary involve-ment in BD is one of the severe and worst prognostic manifestations of the disease.