Abstract: Objective To investigate the effect of X-linked inhibitor of apoptosis protein（XIAP）expression on apoptosis of HepG2 cells induced by 5-fluorouracil（5-Fu）at different concentrations. Methods A eukaryotic expression vector including full length XIAP gene was transferred into HepG2 cells by lipofectin 2000.Reverse transcription-PCR and Western blot were used to examine the mRNA expression and XIAP.Different concentrations of 5-Fu were used to detect the inhibitory rate of HepG2 cells after transfection with XIAP gene. Results The mRNA and protein expression levels were higher and the inhibitory rate of HepG2 cells for 5-Fu was lower in HepG2 cells after transfection with XIAP gene than in control cells. Conclusion XIAP can decrease the apoptosis rate of HepG2 cells for 5-Fu,which may be one of the mechanisms underlying multidrug resistance in liver cancer.