We have analyzed the chemical composition of primary intrahepatic stones from 72 Korean patients. Two types of concretions have been identified: brown pigment (calcium bilirubinate) stones and black-colored mixed stones. Brown pigment stones were found in 68% of all cases and the remainder (32%) consisted of mixed stones. Intrahepatic mixed stones had mean cholesterol and bilirubin contents of 46.6% and 25.9%, respectively, whereas calcium bilirubinate stones had mean cholesterol and bilirubin contents of 14.1% and 43.6%, respectively. Intrahepatic mixed stones had a smooth black-colored surface and on cross section, exhibited a distinct outer shell surrounding an inner yellow, cholesterol-rich body. The finding of intrahepatic mixed stones with high cholesterol content suggests that primary hepatolithiasis may result from at least two different conditions or disorders and points to different approaches to their treatment.