Abstract: ObjectiveTo investigate the effect and its mechanism of genistein(Gen)on human leukemia cell line Jurkat E6-1.MethodsJurkat E6-1 cells were treated with different concentrations of Gen.Inhibitive effect of Gen on cell grow th was determined with methy thiazoly tetazolium(MTT)test.DNA-ladder was used to measure the effect of Gen on apoptosis of Jurkat E6-1 cells.Alternative of bcl-2 and bax genes were detected with reverse transcription polymerase chain reaction(RT-PCR).ResultsAt a concentration of higher than 0.5μmol/L,Gen could inhibit the growth of Jurkat E6-1 cells.After 24 hours,the inhibition ratio was 5.9% compared with that of the control group,with a significant difference (P<0.01)in a time-does-dependent manner(P<0.01).After 72 hours,the inhibition ratio was 24.9%,with a significant difference compared to that of at 24 hours(P<0.01).The expression rate of bcl-2 decreased after the treatment with the increasing concentration of Gen.However,the expression rate of bax increased after the treatment with the decreased concentrations of Gen.ConclusionGen can significantly inhibit the growth of human leukemia line Jurkat E6-1.Its mechanism is up-regulation of the bax expression and dow n-regulation of the bcl-2 expression.