IN THE care of infants with prolonged jaundice, the surgeon is particularly concerned with those suspected of having obstruction of the extrahepatic ducts. In 1927, Ladd was the first to correct successfully congenital atresia of the bile duct system. At that time, and for some time afterwards, there was great enthusiasm and hope that a considerable number of infants with signs of obstructive jaundice could be helped. Unfortunately, events have not proved this to be so. According to various reports, only 2 to 3 per cent of infants with clinical obstructive jaundice prove to have an atresia of the extrahepatic duct system which is amenable to surgery. To select these few patients who have atresia of the extrahepatic duct out of the large number of jaundiced infants is a difficult task. Formerly, it was common practice to subject all these infants to extensive surgical exploration at 6 to 8 weeks of age to be sure that no correctable lesion was overlooked. Gellis was the first to call attention to the fact that these explorations, particularly in infants under 3 months, were not without hazard. Among the cases he reviewed there were some deaths directly attributable to the diagnostic explorations. Consequently, it has become common practice to delay exploration on these infants until they are 5 to 6 months of age. This practice seems reasonable to circumvent the problem of deaths after exploration, for this hazard is a great deal less after the infants are 6 months or more of age.