Abstract: Objective :To study the effect of HBV X protein on the expression of oncogene H-ras in HepG2 cells,and whether lamivudine could affect the expression of oncogene H-ras in HepG2x cells transfected with HBV X gene. Methods :The effect of X protein on the expression of H-ras in HepG2 cells and the effect of lamivudine on the HepG2x HCC cells,transfected by hepatitis B virus,were detected using immunocytochemistry and western blot. Results :X protein could increase the H-ras expression in cellular plasma of HepG2 cells.The optical density value of the area of HepG2x cells was markedly higher than that of HepG2 cells,P0.01,The average optical density value showed similar result.Lamivudine treated group at a concentration of 4.36×10^-4mol/L decreased H-ras expression in HepG2x cells resulted in the gray density value of the area of positive protein band was lower than that of control group,P0.01.But lamivudine didn't have any effect on HepG2 cells. Conclusion :The up-regulation of H-ras in HepG2x cells indicated an enhanced malignancy of the cells.Lamivudine could inhibit the expression of H-ras that denoted lamivudine may prevent the carcinogenesis of HBV X protein.