Objective To observe the effect and mechanism of Keliu Pill （ antitumor pill ） on the growth of human colon car- cinoma cell.Methods The cell proliferation was assessed by methyl-thiazolyl-tetrazolium （ MTT ） assay after 24to 48hours of treatment with different concentrations （ 4

2

1

0.5or 0.25mg / ml ） of Keliu Pill on HT-29cells.The apoptosis was deter- mined with AnnexinⅤstaining and cell cycleand was determined with flow cytometry （ FCM ） .Results Comparing with the control group

Keliu Pill at different concentrations （ 0.5to 4mg / ml ） could significantly inhibit the proliferation of HT-29 cells

with statistical significance in the 48hcellular proliferation inhibition rate （ CPIR ） and optical density （ OD ） value （ P< 0.01 ） .The OD values and 48hCPIRs of Keliu Pill at high concentrations （ 1mg / ml to 4mg / ml ） were superior to those at low concentrations （ 0.25mg / ml and 0.5mg / ml ）

with statistical significance （ P<0.01 ） .Comparing with the group of 1mg / ml

the apoptosis rates were significantly increased in group of 2and 4mg / ml of Keliu Pill （ P<0.05 ） .The apparent hypodiploid area appeared before G0 / G1phase after treatment with 4mg / ml of Keliu Pill

with significant difference as compared with 1mg / ml and 2mg / ml of Keliu Pill （ P<0.05 ） .Conclusion Keliu Pill could inhibit the proliferation and induce the apoptosis of hu- man colon carcinoma cell line HT-29.