To assess the role of extrahepatic biliary obstruction in the production of damage to the liver and biliary ductal apparatus, 100 patients underwent choledochoduodenostomy for malignant or benign extrahepatic biliary obstruction. Patients were observed by means of barium meal studies for one month to one year postoperatively. Emphasis was placed upon the relationship of the appearance, structure and function of the extrahepatic and intrahepatic biliary tree in these studies with the findings after histologic examination of the liver, gallbladder or commmon bile duct wall; liver function tests, and cultures of the bile. It has been shown that barium meal studies are an indicative criterion for the evaluation of the extent and progress of the hepatobiliary damage and of its further development after relief of the obstruction. It has been proved that chronic extrahepatic biliary obstruction of long standing seen in patients with a long history of symptoms, with a high incidence of primary common bile duct stones and with a high rate of contaminated bile as well as a high percentage of common bile duct dilation is a challenging and serious disease for both the patient and the hepatobiliary apparatus.