Objective: To investigate the influence of hepatitis B virus X protein (HBx) on the clock gene expression in normal hepatic cells. Methods: Human normal hepatic L02 cells were transfected with the HBx expression plasmid (pcDNA3.1-HBx) or empty vector plasmid (pcDNA3.1), respectively, then the HBx mRNA and protein expression in L02 cells was determined by RT-PCR method and Western blot analysis, respectively, and the mRNA expression of the clock genes that included CLOCK, BMAL1, Per1, Per2, Per3, Cry1, Cry2 and CKIε in L02 cells were detected by real-time PCR. Results: Results of RT-PCR and Western blot showed that both HBx mRNA and protein were obviously expressed in the L02 cells transfected with HBx expression plasmid, which were not seen in the L02 cells transfected with empty vector plasmid. Compared with L02 cells transfected with empty vector plasmid, the CLOCK and Cry1 mRNA expressions were remarkably increased while the mRNA expressions of BMAL1, Per1, Per2, Per3, Cry2 and CKIε were remarkably decreased in L02 cells transfected with empty vector plasmid, and all the differences had statistical significance (all P<0.05). Conclusion: HBx can change the expressions of clock genes in normal hepatic cells, which may disrupt circadian rhythm of liver cells, and this may be one of the mechanisms for the pathogenesis of liver cancer.