To elucidate the risk factors for hepatocellular carcinoma (HCC) among women, we made a combined analysis of the data from three case-control studies conducted in high-risk areas of Japan. A total of 120 cases and 257 controls were included in the analysis. After adjustment for the study category, age, and other potential confounders, significantly increased risks were associated with chronic hepatitis-B virus infection (odds ratio [OR] = 42.4, 95 percent confidence interval [CI] = 11.2-160.2), a past history of blood transfusion (OR = 3.7, CI = 1.8-7.5), and a history of smoking (OR = 2.2, CI = 12-4.1). In addition, women with a history of heavy drinking experienced an elevated risk of borderline significance (OR = 4.2, CI = 0.9-20.4, P = 0.07). When these ORs were compared with the corresponding estimates among males from the same case-control studies, no significant differences were observed between the two genders. Among the factors examined in this analysis, drinking and smoking habits--which are more common among Japanese men than women--may partly account for a large male-predominance in the incidence of HCC. Further studies are needed to clarify the roles that sex-hormones and hepatitis-C virus infection might play in the large gender difference of HCC occurrence.