The interhepatic duct connecting the right and left hepatic duct is a very rare anomaly of the biliary tree, Only two cases have been reported globally. We report a case of the interhepatic duct in 60 year-old woman. Her chief complaint was intermittent right upper quadrant pain for several years. Endoscopic retrograde cholangiopancreatography revealed an interhepatic duct connecting the right and left hepatic duct. Additionally, there was a low union of the hepatic duct and the cystic duct entered the right hepatic duct. Periampullary diverticulum was also combined. (Korean J Gastrloeaterol 1998;31:829 - 831)