Unexpandable lung due to pleural disease may manifest itself as a hydropneumothorax after pleural drainage procedure or as an inability to completely drain a pleural effusion due to chest pain. The condition is a mechanical complication of a variety of pleural disorders. Of these, malignant lung entrapment and inflammatory lung entrapment are considered complications of active pleural disease, and management is primarily dependent on the nature of the active process. Trapped lung is a sequela of remote inflammation of the pleural space. Trapped lung is usually asymptomatic but may be the cause of dyspnea in some patients. The only available treatment of symptomatic trapped lung is surgical decortication. Surgical decortication should only be considered after other causes of dyspnea have been excluded.