To study the effect of HBx gene on the apoptosis of the cell lines (L02, HepG2) and the interaction between HBx and X-linked inhibitor of apoptosis protein (XIAP), the apoptosis of pcDNA3.1-HBx transiently transfected cell lines (L02, HepG2) was detected by flow cytometry and the mRNA expression of XIAP was assayed by real-time RT-PCR. Our study showed (1) the morphology of L02/pcDNA3. 1-HBx was changed and the appearance of the cells mimicked that of HepG2 cells; (2) HBx gene could be detected in L02/pcDNA3.1-HBx and HepG2/pcDNA3.1-HBx;(3) the apoptosis rate of L02/pcDNA 3.1-HBx was higher than that of L02 cells (P＜0.01) and the apoptosis rate of HepG2/pcDNA3. 1-HBx was lower than that of HepG2 cells (P＜0.05); (4) the XIAP expression in L02 was about 3 times that in L02/pcDNA3.1-HBx cells (P＜0.01), and the expression of XIAP in HepG2/pcDNA3. 1-HBx was about 4 times that in HepG2 (P＜0.01). It is concluded that HBx gene may promote the apoptosis of normal hepatocytes and inhibit the apoptosis of cells of hepatic carcinoma by regulating the expression of XIAP.