AIM:To investigate the effects of inositol hexaphosphate (IP(6)) on proliferation of HT-29 human colon carcinoma cell line. METHODS:Cells were exposed to various concentrations (0, 1.8, 3.3, 5.0, 8.0, 13.0 mmol/L) of IP(6) for a certain period of time. Its effect on growth of HT-29 cells was measured by MTT assay. The expressions of cell cycle regulators treated with IP(6) for 2 d were detected by immunocytochemistry. RESULTS:IP(6) inhibited the HT-29 cell growth in a dose- and time-dependent manner. Analysis of cell cycle regulator expression revealed that IP(6) reduced the abnormal expression of P53 and PCNA and induced the expression of P21. CONCLUSION:IP(6) has potent inhibitory effect on proliferation of HT-29 cells by modulating the expression of special cell cycle regulators.