Necrotizing tracheobronchitis and acute airway obstruction from invasive mycosis developed in a patient who had undergone bone marrow transplantation. The infectious process obstructed the airway and disintegrated the walls of the right mainstem bronchus and pulmonary artery. The airway was cleared using rigid bronchoscopy to extract the detritus. The patient died of hemorrhage after rupture of the pulmonary artery through the right mainstem bronchus.