This article describes the utilization of humidified high-flow oxygen therapy systems, which can comfortably deliver optimal humidified high-flow oxygen therapy, via nasal cannulae, at flow rates of up to 40 litres per minute to adult patients, in hospital or at home. The oxygen is saturated with water vapour at body temperature allowing flow to be well tolerated. First, to set the scene, three clinical scenarios are presented of patients nursed in intensive care, who suffered severe respiratory distress. Respiratory failure is explained, and the need for oxygen therapy set out. Alternative oxygen delivery devices and systems are then outlined, and an example of a high-flow system introduced. Set-up of the system is explained and the need for decontamination propounded. Finally, the benefits of the humidified high-flow oxygen system are exemplified, with particular reference to the critically ill patients presented here.