Basis and Purpose:The presence of peripapillary diverticulum (PPD) can cause some biliary diseases, especially common bile duct stones, and also, literally, can change the technique of endoscopic retrograde cholangiopancreatography (ERCP) and affect the complication ratio of this procedure. In this study, we investigate the effect of localization and position of the papilla according to the diverticulum on the success of therapeutic ERCP procedures.Materials and Methods:The study was conducted prospectively in the patients with naive papillae, who underwent ERCP for a period of 16 months. In all patients, the position of papillae according to the diverticulum (the periphery of the diverticulum is thought as the clock circumference, and the position of papillae is defined as the dials of clock), the success rate of biliary cannulation, total procedure time, overall treatment success rate of ERCP, and the complications are investigated.Results:During this period, 222 (18.5%) of the 1205 enrolled patients who underwent ERCP had PPD. Of the patients with PPD, 123 (55.4%) were female and 99 (44.6%) were male, and the median age was 68.910.1 years. According to the position of the papilla by the diverticulum, 90 (40.5%) patients have it on 7 o'clock position, 64 (28.8%) patients have on 6 o'clock position, 63 (28.3%) patients have on 5 o'clock position, and 5 (2.3%) patients have on 1 o'clock position. In the cases of the papilla on 1 o'clock position according to the diverticulum, cannulation procedures were found to be more difficult than other patients (P<0.05). The presence of the diverticulum did not affect the success of therapeutic procedures and did not increase the ratio of complications.Conclusions:In the presence of PPD, additional cannulation techniques may be required for the procedure. Particularly, the aid of percutaneous techniques may be needed for the papilla on 1 o'clock position.