The use of a helium-oxygen (heliox) mixture in patients with airway obstruction was used as early as the 1930s. Although heliox does not resolve airway obstruction, it decreases airway resistance providing time to allow other treatments to become therapeutic, and thus, possibly preventing the need for intubation and mechanical ventilation. Despite new and advanced treatment options in airway obstruction, heliox continues to be a choice for treatment. It is important for critical care nurses to understand the rationale for the use of heliox, the mechanism of action and administration of heliox. Through a case study, the authors discuss the physical properties of helium and its use in airway obstruction. Nursing management of patients receiving heliox is also reviewed.