Extra corporeal membrane oxygenation (ECMO) is a novel, but invasive, form of life support developed from cardio pulmonary by pass technology. The technique has been used successfully in mature infants with severe respiratory failure since 1975. Where persistent pulmonary hypertension is a complicating problem the improved oxygenation resulting from the use of ECMO has a therapeutic role. Controversy exists, however, with regard to whether ECMO offers any advantage over more conventional life support in terms of improved survival. Descriptive data relating to cost and morbidity suggest no disadvantage from the use of ECMO. It is hoped that the current U.K. collaborative trial will clarify whether ECMO should be considered standard therapy for severe respiratory failure occurring in mature infants.