The authors consider mechanism of biliary dysfunction in cholelithiasis responsible for the development of secondary changes in parenchyma and pancreatic ductal system and effect of cholecystectomy on bile lithogenecity in patients with chronic biliary pancreatitis. A high-precision technique for instrumental diagnosis (endosonography) yielded data on the role of microliths and biliary sludge in pathogenesis of chronic biliary pancreatitis. The necessity to use ursodeoxycholic acid derivatives for the treatment of this pathology is substantiated.