ALTHOUGH bile duct and hepatic venous pressures have been extensively studied, not enough attention has been given to the effects of pressure upon the liver and bile ducts.1-4 The relationship of obstruction, pressure, and infection in the bile ducts to jaundice requires further clarification. It is often assumed that jaundice in patients with cholecystitis may be due to infection or the mixture of bile and pancreatic juice in the biliary system.5 The importance of obstruction and pressure may be overlooked if it is assumed that only infection or chemical cholangitis can cause jaundice. In order to clarify the relationship of biliary pressure to serum enzyme and bilirubin level changes and to the alterations in the liver and bile ducts, experimental biliary obstruction has been compared with clinical findings. Partial and complete biliary obstruction with and without bacterial infection has been produced in dogs. Changes noted have been compared