Double-lumen endotracheal tubes have revolutionized the anesthetic management of patients undergoing thoracic surgery. As experience with the techniques of DLT placement and monitoring progress, an increasing number of uses in the intensive care unit will evolve. Benefit from differential lung ventilation in patients with respiratory failure from unilateral lung diseases and bronchopleural fistulae has been documented in selected instances. Isolation of the lungs to prevent contralateral spread of hemoptysis is occasionally of assistance. Frequent monitoring of DLT position while understanding the physiology of differential lung ventilation will minimize complications with these tubes.