Relationship between parapapillary duodenal diverticulum and biliopancreatic diseases Methods The characteristics of PAD were observed microscopically by duodenoscopic retrograde cholangiopancreatography (ERCP), and the relationship between the development of PAD and biliopancreatic diseases was analyzed. Results The incidence of PAD increased with age, and the incidence of biliary stones was significantly higher in PAD patients than in the non-PAD group (P < 0.001), among which primary common bile duct stones (P = 0.004) and recurrent common bile duct stones after biliary exploration (P = 0.022) were higher than in the non-PAD group. The incidence of biliary stones was statistically significantly different in the PAD group compared with the non-PAD group (P < 0.001). It is concluded that parapapillary duodenal diverticulum may be a cause of biliopancreatic disease.