Helium is an inert gas with unique physical properties that allow it to be used for various respiratory emergencies. Because of its low specific gravity and low viscosity, the passage of helium through the respiratory tract is smoother, more laminar, and less turbulent than either air or oxygen. These properties have prompted the use of helium and oxygen in patients with airway obstructions due to tumor, foreign body, edema, or bronchoconstriction. Helium-oxygen has been used to facilitate bronchoscopy through small diameter endotracheal tubes and to increase the effectiveness of high-frequency jet ventilation. Helium has been successful in the treatment of spinal cord decompression sickness seen in divers. Helium-oxygen mixtures are commercially available and may be useful in the emergency department to treat patients with airway obstruction. This article reviews literature concerning the use of helium-oxygen gas mixtures in the emergency department. Additional research conducted in the future may further define the use of this unique gas mixture in the emergency department.