Abstract: Objective To investigate how phytic acid(inositol hexaphosphateIP₆)induces apoptosis of human hepatoma cell line HepG2 through mitochondrial pathway.Methods Hoechst 33258 method and flow cytometry analysis were used to detect cell apoptosis.Flow cytometry analysis was also designed to investigate the status of mitochondrial membrane potential.Reverse transcription polymerase chain reaction(RT-PCR)was adopted to detect the expression of caspase-3 mRNA.Western blot was used to detect the expression of cytochrome c(Cyt-c)protein.Results The apoptotic morphological changes in the cells exposed to IP₆ were observed.Compared with the control group, IP₆ increased the rate of cell apoptosis(F=342.15, q=2.9-28.53;P<0.05) and the rate increased gradually with the increment of IP₆(P<0.05);IP₆ decreased mitochondrial membrane potential(F=14 802.610, q=101.531-209.237;P<0.05)and the mitochondrial membrane potential decreased gradually with the increment of IP₆(P<0.05);IP₆ increased the expression of caspase-3(F=30.474, q=3.406-9.103;P<0.05)and the expression was increased gradually with the increment of IP₆(P<0.05);IP₆ increased the expression of Cyt-c(F=87.194, q=5.246-15.218;P<0.05)and the expression was increased gradually with the increment of IP₆(P<0.05).Conclusion Phytic acid could induce apoptosis in vitro by decreasing mitochondrial membrane potential and increasing caspase-3 and Cyt-c.