AIM: To investigate the infection and replication of hepatitis B virus (HBV) in primarily cultured human fetal hepatocytes (HFHs). METHODS: The human fetal hepatocytes were cultured in serum-free medium, HBV-positive serum was added into the medium to study the susceptibility of hepatocytes to HBV infection. The supernatant was collected for ELISA assay of HBsAg and HBeAg, and quantitative fluorescence PCR for HBV-DNA assay daily. Albumin and HBcAg, CK8 and CK18 expressions were detected by immunohistochemistry in cultured hepatocytes. Content of lactate dehydrogenate (LDH) was measured to find out the integrity of the cell membrane. RESULTS: A stable hepatocyte culture system was established. HBV could infect the hepatocytes and replicate, and HBcAg expression could be detected by immunohistochemistry in hepatocyte-like cells. HBV- DNA in the supernatant could be detected from d 2 to d 18 and HBsAg and HBeAg were positive on d 3-d 18 after HBV infection. HBV in medium increased from d 0 to d 6 and subsequently decreased as the cells were progressively loosing their hepatocyte phenotypes. CONCLUSION: HBV could infect human fetal hepato- cytes and replicate. This in vitro model allowed a detailed study on early events associated with human HBV entry into cells and subsequent replication. AIM: To investigate the infection and replication of hepatitis B virus (HBV) inrized human fetal hepatocytes (HFHs). METHODS: The human fetal hepatocytes were cultured in serum-free medium, HBV-positive serum was added into the medium to study the susceptibility of hepatocytes to HBV infection. The supernatant was collected for ELISA assay of HBsAg and HBeAg, and quantitative fluorescence PCR for HBV-DNA assay daily. Albumin and HBcAg, CK8 and CK18 expressions were detected by immunohistochemistry in cultured hepatocytes. Content of lactate RESULTS: A stable hepatocyte culture system was established. HBV could infect the hepatocytes and replicate, and HBcAg expression could be detected by immunohistochemistry in hepatocyte-like cells. HBV- DNA in the supernatant could be detected from d 2 to d 18 and HBsAg and HBeAg were positive on d 3-d 18 after HBV infection. HBV in medium increased from d 0 to d 6 and succeeded decreased as the cells were progressively loosing their hepatocyte phenotypes. CONCLUSION: HBV could infect human fetal hepato-cytes and replicate. This in vitro model allowed a detailed study on early events associated with human HBV entry into cells and subsequent replication.