In the last ten years, 17 patients with respiratory failure refractory to standard ventilator therapy have been treated with extracorporeal membrane oxygenation (ECMO) at the Toronto General Hospital. One patient was treated with ECMO twice. Four perfusions were veno-arterial, the remainder veno-venous. Perfusions ranged from 1 1/2 to 19 days, with a mean of six days. Ten patients died during treatment or soon after it was discontinued. Eight patients improved enough to allow resumption of standard ventilation, and four patients recovered sufficiently to have normal arterial blood gas levels on room air. Three are long-term survivors. Multiple surgical procedures have been performed successfully during use of ECMO including lung lavage, open lung biopsy and three lung transplants. Major complications include hemorrhagic diatheses and sepsis. The technique involves a substantial commitment of time and personnel but remains a tenable option for presumed reversible life-threatening respiratory failure.