The neurocognitive outcome for infants with congenital diaphragmatic hernia treated with extracorporeal membrane oxygenation (ECMO) is compared with that of neonates treated with ECMO for other diagnoses. The mean age at the time of the latest assessment (for the 51 survivors with adequate follow-up) was 31 months. The neurological outcomes did not differ significantly. However, the cognitive outcome for infants with congenital diaphragmatic hernia was significantly poorer than for those without it. This was particularly true if the infant with congenital diaphragmatic hernia was a boy and his mother had limited formal education.