An 83-year-old male was referred to us for deranged liver function in December 2010. There was mildly elevated bilirubin level of 36 μmol/L, alkaline phosphatase level of 281 μmol/L, and transaminase level of 98 μmol/L. Tumour markers (carcinoembryonic antigen, alpha-fetoprotein, and carbohydrate antigen 19-9) were normal. Ultrasonography revealed a markedly dilated common bile duct (CBD) and intrahepatic ducts with irregular mural lesions.Endoscopic retrograde cholangiopancreatography (ERCP) showed a grossly dilated CBD and intrahepatic ducts filled with thick mucus and multiple large filling defects. Brush cytology revealed atypical cells. A nasobiliary drainage catheter was inserted for biliary decompression. Bilateral percutaneous transhepatic biliary drainage (PTBD) catheters were later inserted due to inefficient nasobiliary drainage.Further evaluation by computed tomographic scan showed dilatation of the whole biliary system with multiple papilloma-like lesions as shown in Figure 1. The presence of mucus in the biliary tree and image findings raised the suspicion of biliary papillomatosis. In order to localise and assess the extent of involvement, intra-operative choledochoscopy was performed via the PTBD tract. The PTBD tract was serially dilated up to 14 Fr to allow passage of a choledochoscope. Multiple biliary papillomas over the left hepatic duct, hilar bifurcation, and upper main bile duct were visualised. The right biliary system, lower CBD, and ampullary region were disease-free. After thorough assessment by intra-operative choledochoscopy, left hepatectomy and main bile duct excision with right hepatico-jejunostomy via robot-assisted laparoscopic approach was performed.The patient was placed in the reverse Trendelenburg position with legs spread apart, and a 5-to 12-mm subumbilical port was inserted with the establishment of carbon dioxide pneumoperitoneum. After diagnostic laparoscopy, five trocars were