It has been accepted widely that filling defects in cholangiography are attributed to stones or tumors. However, we have recognized that filling defects at the hepatic hilum in cholangiography are caused by compression of the hepatic duct by the right hepatic artery. We studied 125 cases by cholangiography. Of these, 34 cases were subjected to simultaneous percutaneous transhepatic cholangiography and selective visceral arteriography. Among 125 cases, 25 cases (20%) showed filling defects at the hepatic hilum from compression by the right hepatic artery.