The study was aimed to investigate the effects of emodin on proliferation inhibition and apoptosis induction in human chronic myeloid leukemia cell line K562 cells, and to explore the role of P210 protein and activation of caspase 3 in these processes. K562 cells were exposed to emodin at different doses. The proliferation inhibition was detected by MTT assay and colony formation test. The ability of emodin to induce apoptosis and DNA fragmentation were examined by flow cytometry. The expressions of P210, procaspase-3 and PARP protein were determined by Western blot. The results indicated that the emodin remarkably inhibited the K562 cell proliferation, with IC(50) value of 38.25 micromol/L after treatment for 48 hours. Meanwhile induced apoptosis, Annexin V-FITC positive cells, sub-G(1) apoptotic peak and DNA fragmentation in K562 cells confirmed that emodin induced apoptosis in K562 cells in dose-dependent manner. Western blot results showed that emodin inhibited phosphorylation of P210 protein in K562 cells and down-regulated the expression levels of P210. The procaspase-3 level in treated K562 cells decreased with increased expressions of PARP in time-dependent manner. It is concluded that the emodin efficiently inhibits growth and induces apoptosis of K562 cells, while the inhibition of phosphorylation of P210 protein, down-regulation of P210 protein expression and activation of caspase-3 may be involved in these processes.