We present 2 cases of endotracheal tube obstruction as a result of previously aspirated foreign bodies that moved from the bronchial tree into the endotracheal tube. The signs of endotracheal tube obstruction were demonstrated in both cases: (1) activation of the high-pressure alarm; (2) difficulty ventilating by using a bag-valve-mask device; (3) rapid decrease of end-tidal CO2; (4) oxygen desaturation that may have lagged behind the decrease of end-tidal CO2; and (5) the inability to advance a catheter down the endotracheal tube. The differential diagnosis of endotracheal tube obstruction is discussed, as are possible interventions to remove the obstruction and secure an open airway.