Tracheobronchomalacia can be latent without showing any clinical manifestations and may be incidentally found during anesthesia. In such cases, hypoxia may occur during anesthesia. We experienced obstruction of the left main bronchus caused by bronchomalacia that was incidentally found during open-heart surgery in a 4-yr-old patient. We could not reopen the airway by routine techniques, such as positive pressure, and had great difficulty in weaning the patient from cardiopulmonary bypass. The use of a Fogarty catheter allowed the relief of airway obstruction and weaning from cardiopulmonary bypass.