Helium-oxygen (heliox) gas mixtures have been studied for over 70 years as an adjunctive therapy for airway obstruction in a variety of respiratory diseases. The medical use of heliox is based on the physical properties of helium as its low density makes it advantageous in promoting more efficient flow through narrowed passages. Clinical evidence of the efficacy of heliox in treating paediatric respiratory diseases is increasing in the medical literature. This article consists of a comprehensive review of the literature investigating the utility of heliox in the treatment of paediatric respiratory disorders, including upper and lower airway obstruction, mechanical ventilation, and aerosol delivery.