A rare case of pancreaticobiliary maljunction (PBM) without dilatation of the biliary tract (DBT) associated with gallbladder carcinoma is described herein. A 62-year-old European woman with a long history of right upper abdominal pain was diagnosed as having PBM without DBT by endoscopic retrograde cholangiopancreatography and other examinations. Excision of the gallbladder and biliary duct with a Roux-en-Y hepaticojejunostomy was performed, and subsequent pathological examination of the surgical specimen showed a well differentiated adenocarcinoma of the gallbladder. She had no clinical symptoms for 58 months postoperatively. PBM allows reflux of pancreatic juice into the biliary tract. Recent findings support the idea that epithelial hyperplasia plays an important role in gallbladder carcinogenesis with PBM, and also support the concept that gene mutations are involved in the carcinogenesis of biliary epithelium in patients with PBM. For these reasons, we advocate that resection of the extrahepatic biliary tract in PBM patients without bile duct dilatation, rather than cholecystectomy alone, is the treatment of choice for preventing bile duct carcinoma.