THE CHILD BORN with a markedly distended abdomen presents a startling and challenging picture. Abdominal distention at the time of birth has been described infrequently, and many textbooks of pediatrics, pediatric surgery, and newborn care fail to mention the syndrome. There are, however, several well-documented causes for the syndrome, many of which require immediate diagnosis and treatment if life is to be preserved. The obstetrical problem of dystocia which such children encounter has been recently reviewed,1 as has the roentgenologic diagnosis of neonatal ascites.2 However, the problems of diagnosis and management which such children present in the neonatal period have received scant attention. The two patients reported here illustrate some of the problems. In addition, these patients provided an opportunity to study the mechanisms by which ascites is produced in infants with urinary tract obstruction. Report of Cases Case 1.—A 7 lb 7 oz (3,373 gm) boy was