Plastic bronchitis is a rare disorder characterized by the formation and, sometimes dramatic expectoration of long, branching bronchial casts. DIsorders associated with bronchial casts either produce an increase in the volume or viscosity of secretions, such as allergic bronchopulmonary aspergillosis, asthma, cystic fibrosis, pneumonia, and chronic bronchitis; or there are obstructions or structural abnormalities that decrease mucous clearance, such as bronchiectasis. The diagnostic evaluation should include serum laboratory studies, specimen cultures, skin tests, chest radiograph and CT scan, pulmonary function tests, and bronchoscopy. Therapy should be directed towards the underlying disorder and should also include maneuvers to facilitate removal of casts to prevent complications, such as secondary pneumonia.