BACKGROUND: Anatomic unexpected variations in biliary tree may be discovered during laparoscopic cholecystectomy. CASE REPORT: A 57-year-old man was admitted for abdominal pain, vomiting and mild jaundice. Abdominal ultrasonography revealed a gallbladder containing multiple stones and biliary sludge. All pre-operative investigations showed no anatomical variations in extrahepatic biliary tree. During surgical intervention an accessory extrahepatic duct, connecting the IV segment of the liver to the fundus of gallbladder, was discovered. CONCLUSIONS: Pre-operative routine investigations for gall stones diseases may not reveal anatomic variations of biliary tree.