Reinforced endotracheal tubes (ETTs) are designed to resist kinking or compression. However, these have a potential risk of being obstructed or severed by a patient's bite. We report a case in which a reinforced ETT was severed by tube-bite while the patient was in the prone position during an intensive care unit stay. Bronchoscopic evaluation showed that the severed distal part of the tube had lodged in the patient's right main bronchus, and it had to be surgically removed. The patency of reinforced ETTs should be carefully monitored in patients intubated in the prone position.