The main causes of cholangitis are hypertension in the biliary ducts and infection. In order to determine the place of the infectious factor in the acute cholangitis development, a retrospective and prospective analysis of case histories of 176 patients with choledocholithiasis and manifestations of acute and chronic cholangitis was performed. Bile from the common bile duct in the patients with obstruction of the biliary tract was studied. In the patients with mechanical jaundice without and with cholangitis, the intraductal pressure in the common bile duct averaged 227.3±26.1 mm of water column, in the patients without signs of cholangitis that was 97.5±8.3 mm of water column. With mechanical jaundice without acute cholangitis, it was slightly elevated if compared to normal. This suggests that the increase in pressure in the bile ducts in acute cholangitis is not influenced by the fact of obstruction of the biliary tract, and the development of the inflammatory process in them. In the patients with cholangitis, the initial values of the number of colonizing units were much higher than in "pure" choledocholithiasis. After endoscopic papillosphincterotomy in the patients with vivid clinical cholangitis, in whom decompression was achieved, in the control study, this value decreased by 100−500 times, which was accompanied by clinical improvement. According to the results of the study, it was noted that in the patients with a manifested clinic sign of cholangitis there is a significant decrease in the number of colonizing units on the third day after endoscopic papillosphincterotomy. At the stone stuck in a papilla the choledoch turns into so−called analog of an abscess. The opening of the papilla provides a free passage of the contents of the choledochus (i.e. pus) into the duodenum, so there is an almost instant therapeutic effect. The increase in pressure in the bile ducts in acute cholangitis is influenced by the development of an inflammatory process, which indicates the manifestations of biliary infection. The presented research has a prospective character and needs further development. Key words: cholangitis, biliary infection, intraductal pressure, bile.