BACKGROUND Nasal CPAP is often very effective in preterm infants as the initial means of respiratory support, but a sub-group of infants, most with features of respiratory distress syndrome, fail on CPAP and require intubation and ventilation in the first 72 hours. When compared to those in whom CPAP is successful, infants failing CPAP have a substantially longer duration of respiratory support, and a higher risk of adverse outcomes. Decreasing the risk of CPAP failure would thus seem advantageous, and may be achievable with minimally invasive surfactant therapy (MIST), in which surfactant is administered to a spontaneously breathing infant who then remains on CPAP. A technique of MIST (the "Hobart method") using a semi-rigid surfactant instillation catheter has been shown to be feasible in preterm infants on CPAP, and appears to have the potential to alter respiratory course and outcome. This method of MIST now requires evaluation in randomised controlled trials.