Extracorporeal membrane oxygenation (ECMO) was used for 28 patients (14 children and 14 adults) over a 5 yr period. Nine patients improved on ECMO and 5 were long-term survivors. ECMO was used for pulmonary insufficiency in 24 patients. Initially, only moribund patients were treated, but recently the combination of open lung biopsy and pulmonary insufficiency index (PII) was used to select patients. The best results were obtained in newborn cases and the adult capillary leak syndromes; the major problem was progression to fibrosis despite ECMO support. ECMO was used for cardiac failure in 4 patients. Children with postoperative cardiac failure did the best; profound shock was not reversed with venoarterial bypass. ECMO support was lifesaving in selected cases of pulmonary insufficiency. Initial trials in cardiac failure and the infant age group suggested that ECMO will have an even greater role in those applications.