We reviewed a 22 year experience with 138 newborn infants with congenital evisceration through defects of the abdominal wall. Omphalocele is a large defect which always has a sac, in which the rectus muscles insert laterally on the costal margins and which usually has associated anomalies. Cord hernia is a small defect which always has a sac, in which the rectus muscles insert at the xiphoid and which commonly has associated anomalies. Gastroschisis is a small defect which never has a sac, in which the rectus muscles insert at the xiphoid and has few associated anomalies, though prematurity is frequent. We hypothesize that gastroschisis develops because the umbilical coelom fails to form, which forces the elongating midgut to rupture into the amniotic cavity. This differs from the embryogenesis of omphalocele, which is failure of closure of a primary body fold, and from that of cord hernia, which is failure of the midgut to return from the umbilical coelom. The number of infants in this series who survived after surgical repair of an omphalocele was 31 of 51 patients; of a cord hernia, 22 of 28 patients, and of gastroschisis, 40 of 59 patients. Factors contributing to mortality were associated anomalies, low birthweight and surgical closure under excessive tension.