To assess the role of hepatitis B e antigen (HBeAg) and its interaction with hepatitis B surface antigen (HBsAg) on the development of hepatocellular carcinoma (HCC), this case-control study included 361 age- and sex-matched pairs of patients with histologically proven HCC and healthy control subjects. HBsAg, HBeAg and antibody to HBeAg (anti-HBe) were detected by radioimmunoassay. Antibodies to hepatitis C virus (anti-HCV) were detected by second-generation enzyme immunoassay. The prevalences of HBeAg (20.2%), HBsAg (80.3%) and anti-HCV (29.5%) in cases were higher than in controls (1.9%, 20.7%, and 2.7% respectively; each P < 0.0001). Using patients negative for HBsAg, HBeAg and anti-HBe as a referent group, univariate analysis indicated that HBsAg alone or HBsAg and HBeAg were risk factors for HCC (P for trend < 0.0001). Calculation of incremental odds ratio indicated that there was additive interaction between HBsAg and HBeAg. Multivariate analysis indicated that HCC development was strongly associated with the presence of HBeAg (odds ratio, 8.1; 95% confidence interval, 2.4-27.1), HBsAg (odds ratio, 68.4; 95% confidence interval, 20.5-227.8) and anti-HCV (odds ratio, 59.3; 95% confidence interval, 13.6-258.4). In conclusion, HBsAg, HBeAg and anti-HCV are independent risk factors for HCC. There is additive and independent effect modification between HBsAg and HBeAg on the development of HCC.