Organic disease of the liver can cause cholestasis by mechanical hindrance at any level from the bifurcation of the common hepatic duct to the septal bile ducts within the small portal tracts; moreover, protracted cholestasis from any cause provokes enough inflammatory exudation and connective tissue formation to add a secondary intrahepatic mechanical obstructive component. The more difficult problems in differential diagnosis are presented by cases in which cholestasis occurs without tangible mechanical explanation. Certain drugs, endocrinopathies, and viral infections must then be considered as possible causes. The biliary concrements found in children with the "inspissated bile syndrome" are probably the result rather than the cause of obstructive phenomena. Liver biopsy is sometimes helpful in diagnosis, but at times surgical exploration or percutaneous cholangiography becomes necessary.