A review of 19 original studies on the use of high-flow nasal cannula was conducted by investigators from Melbourne. Both randomized and non-randomized studies were included. The definition of ‘high-flow’ was variable, but one definition was a flow of greater than 1 L per minute. High-flow nasal cannulae were used for a range of indications, including primary support of RDS. HFNC delivers distending pressure but this varies according to the amount of leak (around the prongs and from the mouth), and increases with higher flow rates and with a smaller infant size. There is uncertainty about the efficacy and safety of this modality of therapy. Randomized trials of HFNC are in progress.