Congenital tracheal stenosis (CTS) is a rare disease associated with high mortality and morbidity, especially if it is associated with intracardiac anomalies or vascular rings. Heliox, a "carrier gas" with low density, has been used in pediatric intensive care units for treating acute respiratory failure due to obstructive airway disease. Here we report a 3100-g, 39-week newborn with long-segment CTS complicated with a pulmonary artery sling and tetralogy of Fallot, to whom heliox was given as the rescue therapy during near-complete airway obstruction and cardiopulmonary failure. Although this patient finally died from failure of corrective surgery, our experience with heliox has suggested that its effects in improving oxygenation and eliminating CO (2) can be a rescue strategy in a mechanically ventilated infant with severe airway obstruction.