Anesthesia for biopsy or excision of mediastinal masses is associated with a high risk for severe airway obstruction, hemodynamic compromise, and death. Extrinsic compression of the trachea or mainstem bronchi, occurring usually with anterior mediastinal masses, causes significant airway obstruction and is a cause of death or morbidity with induction of or emergence from anesthesia. Although anesthesiologists are aware of the risks for airway compression, little emphasis is placed on the frequency and morbidity of cardiovascular impairment caused by anterior and visceral mediastinal masses.