The actual hypothesis on the etiology and pathogenesis of neonatal hepatitis, intrahepatic and extrahepatic biliary atresia and choledocal cyst is that these disorders can be different results or permissible outcomes of a single basic process: infantile obstructive cholangiopathy. This hypothesis can explain the failure of many infants with operable extrahepatic biliary atresia to do well following surgically successful anastomosis. Very possibly no surgical mode of therapy will cure a significant fraction of infants with biliary atresia (correctable and non-correctable types) because the basic disease process actually produces portal fibrosis and destroys intrahepatic bile ducts as well. However, since the obliterative process can resolve, even if not usually completely, surgical procedures of conventional or of hepatic-portoenterostomy type should be considered for all infants who are found to have biliary atresia. Probably biliary atresia is more in need of preventive or prophylactic measures than of new surgical procedures.