Essential phospholipid PPC was administered to male rats over 24 and 72 hours after operation on bile duct ligation. The subsequent alterations were studied by ultrastructural morphometry and correlated with serum enzyme changes. By the results evidence is accrued that hepatocellular mitochondria are prevented by phospholipid treatment to develop alterations as seen after bile duct ligation alone. This occurred although serum GLDH activity was significantly increased. The smooth endoplasmic reticulum exhibited a normotrophic behavior after PPC treatment of animals in which bile duct ligation was done. The surface of the rough membranes was found increased at hours 24 and 72 after bile duct ligation. The bile canaliculi were markedly dilated. However, this alteration was not accompanied by a marked loss of microvilli. Administration of the phospholipid induced a numerical increase of hepatocellular nuclei in both sham-operated and cholestatic animals independantly from the bile duct ligation. It is suggested by the results that the administration of the phospholipid PPC is of value in influencing the fine structural hepatic alterations as seen in cholestatis.