Complications of extracorporeal membrane oxygenation in neonates. In cases of severe respiratory failure, cardiopulmonary bypass has been used as support until cardiac and pulmonary recovery occurs. We report the Wilford Hall USAF Medical Center experience with extracorporeal membrane oxygenation (ECMO) and its associated complications. From July 1985 to March 1989, 57 neonates were placed on membrane oxygenators. The overall survival was 79%. Technical complications encountered included catheter-related problems, mechanical complications of the pump apparatus, and hemorrhage. Hemorrhagic complications were the most frequent and devastating complications encountered. Intracranial hemorrhage accounted for six deaths associated with bypass. Extracorporeal membrane oxygenation is successful in significantly improving survival of neonates whose predicted mortality approaches 100% with conventional treatment. The rate of infant mortality using the membrane oxygenator is not affected by technical complications related to catheter position, mechanical problems with the circuit, or hemorrhage, excluding intracranial hemorrhage. The major cause of death of infants receiving extracorporeal membrane oxygenation is the underlying disease process leading to cardiopulmonary failure. 