Tubulovillous adenomas are common in the colon and rectum, but are rare in the common bile duct. Biliary adenomas may produce obstructive jaundice, which can be easily confused with a malignant neoplasm or stone. We report a case of a carcinoma in situ arising in a tubulovillous adenoma of the distal common bile duct causing obstructive jaundice. A 55-year-old male presented with a 10-d history of pruritus and progressive jaundice. Abdominal sonography and computed tomography showed a mass in the distal common bile duct. Endoscopic retrograde cholangiopancreatography showed luminal narrowing of the bile duct due to a polypoid mass. Positron emission tomography demonstrated no abnormal uptake. It was thought that this mass was a malignant tumor, thus a pylorus-preserving panceaticoduodenectomy was performed. The final pathology showed a tubulovillous adenoma with carcinoma in situ of the distal common bile duct. At follow-up 8 mo later, endoscopy showed multiple polyps in the rectum, colon and stomach. The polyps were removed by endoscopic mucosal resection and shown to be tubular adenomas with high grade dysplasia. Biliary adenomas require careful follow-up for early detection of recurrence and malignant transformation. Tubulovillous adenomas are common in the colon and rectum, but are rare in the common bile duct. Biliary adenomas may produce obstructive jaundice, which can be easily confused with a malignant neoplasm or stone. We report a case of a carcinoma in situ arising in a tubulovillous adenoma of the distal common bile duct causing obstructive jaundice. A 55-year-old male presented with a 10-d history of pruritus and progressive jaundice. Abdominal sonography and computed tomography showed a mass in the distal common bile duct. Endoscopic retrograde cholangiopancreatography showed wasinal that this mass was a malignant tumor, thus a pylorus-preserving panceaticoduodenectomy was performed. The final pathology showed a tubulovillous adenoma with carcinoma in situ of the distal common bile duct. At follow-up 8 mo later, endoscopy showed multiple polyps in the rectum, co The polyps were removed by endoscopic mucosal resection and shown to tubular adenomas with high grade dysplasia. Biliary adenomas require careful follow-up for early detection of recurrence and malignant transformation.