Abstract: Objective To discuss the characteristic changes of leukemia cell line K562 on replicative senescence induced by ginsenoside Rg1. Methods The effect of Rg1 on the leukemia K562 cell line proliferation was detected by MTT colorimetric test in order to screen optimal time and drug concentration induced cells senescence. The flow cytometry method was used to analyze the cell’s cycle. The percentage of positive cells, the telomere length and the expression of the senescence -related proteins P21,P53,Rb were detected by SA-β-gal staining, southern blotting and western blotting methods, respectively. The ultrastructural senescence changes were observed under the a transmission electronic microscope. Results The optimal time and concentration in order to inhibit the proliferation of K562 cells were 48hours and 20mol/L respectively. The K562 cells arrested G2/M phase. The percentage of positive cells was increased (EM>P/EM> <0.05 ). The senescence -related proteins were up-regulated (EM>P/EM> <0.05). The telomere length became shorten quickly ( EM>P/EM> <0.05 ). Conclusion Rg1 may induce leukemia cell line K562 into the state of replicative senescence by the ce

Key words: Ginsenoside Rg1, Leukemia, K562 cell line, Replicative senescence, SA-β-Gal staining, MTT, Human