An attempt is made in this review to update the reader on recent developments and progress in the study of cholangiocarcinoma: a major primary carcinoma of the liver with a very poor prognosis. Knowledge of the cell biology and physiological functions of the cholangiocyte has recently so progressed that our understanding of cholangiocarcinogenetic mechanism is expected to follow. The first part of the review deals with semantic problems, temporal changes in the incidence of cholangiocarcinoma and geographic differences in epidemiology, etiologic factors (particularly opistorchiasis in Thailand and hepatolithiasis in the Far East), and discusses a recently disclosed role of hepatitis C virus infection (30% of cholangiocarcinoma patients have antibodies against hepatitis C virus in Japan).