Intrahepatic cholestasis associated with both gram-negative bacterial infections and total parenteral nutrition (TPN) is observed more frequently in neonates than in older children or adults. Factors involved in the pathogenesis of this syndrome are uncertain. The cholestatic effects of gram-negative bacterial infections appear to result from the inhibitory effects of endotoxin on bile flow. Since the adverse effects of both endotoxin and TPN on bile flow involve primarily the bile acid-independent portion, the immaturity of the neonatal hepatic excretory system which an inadequate bile acid-dependent fraction of bile would explain the increased susceptibility of the neonate to endotoxin- and, perhaps, to TPN-induced cholestasis.