A pancreaticobiliary maljunction (PBM) is synonymous with abnormal union of the pancreaticobiliary ducts (AUPBD), anomalous arrangement of the pancreaticobiliary ductal system, etc. PBM is a congenital anomaly defined as a union of the pancreatic and biliary ducts located outside the duodenal wall. Free reflux of pancreatic juice up to the biliary tree and/or bile up to the pancreatic duct occurs. Accordingly, various pathologic conditions occur in the biliary tract and pancreas. Although the common channel is long in most cases, some patients have more complicated junctions of the pancreatic and bile ducts. We report a case of PBM with choledochal cyst and stones of the pancreaticobiliary duct in a 39 year-old woman. (Korean J Gastrointest Endosc 2004; 28:107111)