Hepatolithiasis is a major disease in Asia but differences in operative incidence between countries have not been examined. A retrospective study was conducted in Taiwan, Hong Kong, and Singapore, and the results were compared with those in Japan with the aim of defining factors involved in the etiology of the condition. In order to ensure uniformity of the data collected, the same form was used throughout the study and was completed by the same personnel after reviewing the patient's record and radiographs in each case. The years 1976-1980 were chosen for the study, since the newer methods of diagnosis such as ultrasound, endoscopic retrograde cholangiography, and percutaneous transhepatic cholangiography became available during that period. The most significant finding was the difference in the relative prevalence of hepatolithiasis as a proportion of all gallstone cases in Taiwan, Hong Kong, and Singapore, where the majority of the population consisted of patients of Chinese descent. The highest prevalence, 53.5%, was found in Taiwan, while in Hong Kong it was 3.1% and in Singapore 1.7%. Environmental rather than ethnic factors are implicated in the cause of hepatolithiasis.