Plastic bronchitis is a rare, underdiagnosed and potentially fatal condition. It is characterised by the formation and expectoration of branching gelatinous plugs that assume the shape of the airways. These airway plugs differ from the allergic mucin that characterises allergic bronchopulmonary aspergillosis and mucoid impaction of the bronchi. Plastic bronchitis is most often encountered in the paediatric population following corrective cardiac surgery, such as the Fontan procedure. It also occurs in adults. Plastic bronchitis in adults is rare, heterogeneous in its aetiology, and can lead to respiratory distress or even life-threatening airway obstruction. Plastic bronchitis in adulthood should not be overlooked, particularly in patients with chronic inflammatory lung diseases. This review presents current understanding of the presentation, aetiology, pathogenesis, pathology and management of plastic bronchitis in adults.