Of 570 ERHP performed in patients with biliary tract and pancreas diseases, duodenal diverticuli were found in 67 (11.8 per cent). Diverticuli were more frequently diagnosed in patients beyond 60 years of age (67.2 per cent). In 83.6 per cent the diverticuli were single, mostly measuring 15-30 mm and localized in the peripapillary area (70 per cent). ERHP was successful in 85 per cent. Diverticuli were most frequently accompanied by stenosing papillo-odditis (82 per cent), cholecystitis (67 per cent), common bile duct calculosis (58 per cent), followed by pancreatitis (37 per cent) and cancer of the bile ducts (4.5 per cent). Endoscopic treatment was conducted in 46 cases: endoscopic sphincterotomy, hydrostatic balloon dilation of narrowed segments, hydrostatic balloon extraction of calculi, mechanical lithotripsy, nasolabial drainage and endoprosthesis. Significantly lower was the technical success of endoscopic sphincterotomy (78 per cent) when compared with its performance in patients without diverticuli (99 per cent). In spite of this, complex endoscopic treatment resulted in significant fall of bilirubin level (t = 6.58; p less than 0.0001), of AP (t = 8.15; p less than 0.001), of GGJP (t = 6.99; p less than 0.0001), of AcAT (t = 7.14; p less than 0.01). The incidence of complications (6.5 per cent) was not higher than the one observed in patients without diverticuli. In conclusion, endoscopic treatment of bile duct diseases is recommended to be performed also in patients with diverticuli, especially in adult patients and in those exposed to increased operative risk.