The substantial morbidity and mortality of congenital diaphragmatic hernia (CDH) is attributed to the pulmonary hypoplasia caused by the presence of abdominal viscera in the chest during intrauterine life. Recent experimental studies suggest that surfactant deficiency may also contribute to CDH pathophysiology. Clinically, the amniocentesis-derived lecithin to sphingomyelin (L/S) ratio and phosphatidylglycerol (PG) data are used to assess fetal lung maturity. We have performed amniotic fluid phospholipid analyses at 33 to 38 weeks' gestation in 18 fetuses with prenatally diagnosed CDH to assess fetal lung maturity, plan optimal timing for delivery, and selectively employ prenatal glucocorticoid or postnatal surfactant therapy. Compared with published control values from uncomplicated pregnancies, there was no difference in the L/S ratio or PG in the CDH fetus. Based on amniotic fluid phospholipid data, the human CDH fetus is not surfactant-deficient.