Objective To investigate the apoptosis inducing effect of peroxisome proliferator-activated receptor r(PPARr)agomst on leukemic K562 cells and its mechanisms of action.Methods K562 cells in culture medium in vitro were given different concentrations of PPARragonist rosiglitazone(RGZ)(20-80 umol/L)for O,24,48 and 72h The inhibitory rate of the cells were measured by MTT assay,cell apoptosis was detected by Annexin V/PI staining,and the expression of P53 protein as well as the activity of caspase-3 were also detected.Results RGZ(over 40umoL/L)could inhibit the growth of K562 cells and cause apopto-sis remarkably,the suppression Was both in time-and dose-dependent manner.The expression of P53 pmtein was upregulated and the activity of caspase-3 Was increased concomitantly after the cells werle treated by RGZ.Conclusion PPARr agonist RGZ(over 40 umol/L)can induce apoptosis on K562 cells signifieantly,upregu-lation the expression of P53 protein as well as increasing caspase-3 activity may be one of its most important mechamisms.