Abstract: This study is to investigate the effect of the C₂₁ sterols on inducing apoptosis of hepatocellular cancer cells and its potential mechanism. The transplanted model of hepatoma substantiality (Heps) was established in mice, and the mice were divided into four groups: negative controls group and C₂₁ sterols groups (10, 20, 40 mg·kg^-1), treated with drugs separately once a day for 9 days. Then the mice were sacrificed, the tumor growth inhibition rate (IR) was calculated and tumor tissue samples were taken and examined under electron microscope. The tumor cells were harvested and cell viability or apoptosis was analyzed by acridine orange and ethidium bromide (AO/EB) stain. B-cell lymphoma/leukemia-2 gene (bcl-2) in tumor cells was inspected by immunohistochemistry. After treatment with C₂₁ sterols (10, 20, 40 mg·kg^-1), inhibitory effect on the transplanted Heps was observed．The IR was 34.79%, 47.08% and 50.23%, respectively. Apoptosis induced by the C₂₁ sterols was observed, low growth density and some apoptotic cells were observed in tumor under the electron microscope. The expression of bcl-2 gene on tumor cells decreased in the C₂₁ sterols groups, but the percentage of positive area is higher in 40 mg·kg^-1 group than that in 20 mg·kg^-1 group, which differed from apoptosis results. Inhibiting the excessive expression of bcl-2 gene to promote apoptosis may be one of anti-tumor mechanisms for the C₂₁ sterols in Baishouwu.