Obstructive jaundice in infancy and childhood can arise from a variety of causes. Recognition of the importance of persistent jaundice beyond 2 weeks of age in the infant or elevation of the conjugated bilirubin more than 2 mg/dl will allow the timely evaluation of neonates with possible biliary atresia prior to the development of irreversible hepatic damage. Episodes of intermittent jaundice or persistent conjugated hyperbilirubinemia should be investigated at any age to exclude obstructive lesions of the extrahepatic biliary tract. In all cases, a rapid but carefully coordinated evaluation can be undertaken by a pediatric gastroenterology and surgical team, allowing optimum economy of effort and preservation of hepatic function. In nearly all cases with obstructive lesions of the extrahepatic biliary tree, satisfactory hepatic function can be preserved through appropriate surgical intervention. Results with biliary atresia continue to improve but are dependent on early diagnosis and treatment. In cases in which hepatic function deteriorates and hepatic failure becomes inevitable, orthotopic hepatic transplantation can be lifesaving and should be undertaken prior to the onset of irreversible hepatic decompensation. Although the terminology may be somewhat confusing and its etiology uncertain, the entity of choledochal cysts, taken within the context of its modern classification, accurately describes a group of cystic anomalies of the extrahepatic (and intrahepatic) biliary tree, which have many common features. The vast majority can be expeditiously dealt with by surgical excision and hepaticoenteral reconstruction. Two particular associations with choledochal cysts are important to note. When it occurs with infancy, choledochal cysts can be difficult to diagnose, but very important to define and treat expeditiously in order to prevent serious impairment of hepatic function. In all patients, but particularly in adults, the risk of associated carcinoma necessitates extremely careful definition of the biliary tree and urges one to advocate complete excision of the cyst at initial operation.