Cholestasis means reduced flow of bile between hepatocytes and duodenum. Functional as well as mechanical factors may be important in the pathogenesis of cholestatic syndromes. Extra- and intrahepatic cholestasis can be distinguished. Intrahepatic bile ducts use to be dilated in extrahepatic cholestasis after early infancy; they are however not dilated in obstructive jaundice of the newborn. Neonatal cholestatic syndromes caused by liver cell diseases may in addition cause an obstruction of extrahepatic bile ducts. At the present time most workers in the field do believe that extrahepatic cholestasis in the newborn is rather due to inflammation than to congenital malformation.