AIMS: To investigate the effect of Ginkgo biloba extract (EGb761) on cell proliferation and apoptosis in human colon cancer cells.METHODS: Human colon cancer cell lines (HT-29) were cultured and incubated with various concentrations (0-320 mg/l) of EGb 761 solution for up to 72 h. Cell viability, cell apoptosis, cell cycle, expression of caspase-3, the mRNA levels of p53, and Bcl-2 were assessed.RESULTS: EGb 761 inhibited the growth of HT-29 cells in a time-dose-dependent manner. At 80 and 320 mg/L, EGb 761 increased the number of cells in the G0/G1 phase and reduced cells in the G2/M and S phase. EGb 761 treatment also increased the apoptosis ratio of the HT-29 cells. EGb 761 treatment was associated with an increase in caspase-3 activities, reduction in bcl-2 mRNA expression and elevation in p53 mRNA expression.CONCLUSION: EGb 761 inhibits the progression of human colon cancer cells. Its therapeutic effect may be related to enhanced caspase-3 activities, up-regulation of p53 and down-regulation of bcl-2 genes.