Necrotizing tracheobronchitis (NTB) is an acute inflammatory lesion of the lower airway which can result in total airway obstruction. While potentially treatable, this lesion has been described predominantly in autopsy or animal studies. We observed clinical symptoms which reflect development of this lesion. Symptoms of acute airway obstruction (hypercarbia, respiratory acidosis, decreased chest wall movement) occurred in eight neonates undergoing treatment with high‐frequency jet ventilation; five patients treated with HFJV were studied without signs of obstruction. Emergency bronchoscopy using a rigid bronchoscope was performed in the intensive care unit. The diagnosis of NTB was made by the observation of hyperemia, intraluminal debris, or the appearance of eschar formation. Necrotic debris was removed using forceps and/or suction as necessary. All patients survived treatment. Seven were long‐term survivors, all with bronchopulmonary dysplasia. In patients who died, autopsy evaluation of the airway revealed a characteristic picture consisting of necrosis, neutrophil infiltration, epithelial erosion, and intraluminal obstruction. NTB is a newly recognized cause of sudden, potentially fatal airway obstruction. Treatment consists of emergency bronchoscopy and removal of intraluminal debris. All survivors had bronchopulmonary dysplasia.