The authors undertook undertook a study to determine whether CT density evaluation could make a contribution on the improvement of diagnosis and treatment in intrahepatic duct stones. The densities of nineteen stones and the liver parenchyme were measured in pre and post enhanced scans of fifteen patients. Stone-to-liver ratios were also calculated. In vitro CT scans were done on nineteen patients with intrahepatic duct stones. This group included ten cases with pre-operative scans, with subsequent stone removal at surgery or by basket extraction. The mean densities of intrahepatic stones were 79.9 H.U. on in vivo pre-contrast CT, 81.5H.U. in vitro CT, and 96.5 H.U(20%) contrast enhancement of stones was seen on post-enhanced CT. Therefore, in our study per-contrast CT scan was more effective in detecting intrahepatic duct stones. All removed stones had inhomogeneous densities with smooth, irregular or rimmed margins except one homogeneous case from the in vitro CT group.