Among neonates treated with ECMO, those with congenital diaphragmatic hemia(CDH) are reported to have higher mortality and higher frequency of severe neuromotor delay than neonates with other diagnoses. In order to determine predictors of mortality and severe neuromotor delay (Bayley MDI, PDI, or Stanford Binet; IQ ≤ 70) in infants treated with ECMO, we analyzed primary diagnosis, hospital course, and demographic variables for their associations with mortality and ultimate neurodevelopmental outcome. The study population consisted of all 194 infants placed on ECMO at our institution between November 1987 and June 1994. Primary diagnoses were CDH in 39 infants, meconium aspiration syndrome in 73, sepsis in 41, idiopathic pulmonary hypertension in 28, and other diagnoses in 13. Mortality rate for diagnostic categories other than CDH did not differ, and for further analyses non CDH infants were considered as a single group. Mortality rate in the CDH infants was higher than in non CDH group (46% vs 13%, p< 0.001, χ2). In the CDH group, mortality was significantly associated with shorter gestational age, lower 1′ Apgar score, and hemorrhagic complications while on ECMO. In non CDH infants, mortality was associated with metabolic acidosis and hemorrhagic complications. When survivors were compared, CDH infants started earlier and required ECMO for a longer period of time, had a higher incidence of mechanical complications during ECMO, required more days on mechanical ventilation, and had a longer hospital stay. 124 infants (80% of survivors) have been followed for ≥ 1 year. The incidence of severe neuromotor delay did not differ between CDH and non CDH infants (24% vs 15%, p=0.47,χ2). Neonates with CDH had a higher mortality rate and more complicated and prolonged hospital courses than the other ECMO patients. However, in our population, CDH was not a risk factor for severe neuromotor delay.