Pulmonary abnormalities in cystic fibrosis result from the obstruction of small bronchi by highly viscous mucus. Chronic obstructive lung disease and recurrent pulmonary infections result in a typical radiographic pattern later in the disease. Most patients can now be expected to survive into adulthood. The radiologist must make a careful comparison of serial films in order to detect complications early. By far the most important imaging modality is the conventional chest radiograph. CT is more sensitive for detection of structural abnormalities of the lung. Bronchography is a dangerous procedure and can lead to rapid deterioration of lung function. Lung scanning is a very sensitive method for demonstrating regional disturbances of ventilation and may reveal abnormalities earlier than conventional radiographs. In severe hemoptysis, selective bronchial arteriography with embolization of the bleeding vessel can be a life-saving procedure.