Over the last years, several observational studies have suggested that extracorporeal lung assist (ECLA) may be an important contribution to clinical algorithms for the treatment of most severe acute respiratory distress syndrome (ARDS). Today ECLA is used only as a rescue therapy in life threatening gas exchange disorders if maximal conventional therapy fails to prevent from hypoxemia. With subsequent reduction of complications and improvement of biocompability, extracorporeal membrane oxygentation (ECMO) indications may be extendend to treat patients earlier and not only in rescue situations along the original idea to buy the lung some time to heal by avoiding further ventilator associated lung injury. Veno-venous ECMO therapy at present is an important therapeutic option in severe ARDS with persisiting life threatening gas exchange disorder as a rescue therapy. The development of smaller, less complex and more secure ECMO or pumpless veno-arterial ECLA systems has the potential to perform controlled studies of its use in ARDS and potentially expand indications.