Objective To investigate the effect of TRAIL on NB4 and K562 cell lines, and its relationship with TRAIL releptors.Methods Jurkat cells were used as positive control,NB4 and K562 cells were treated with different concentrations of TRAIL. Cell morphologic changes were monitored. The cell proliferation was evaluated by MTT assay. The expression of TRAIL receptor were determined by flow cytometry.Results MTT assay showed that TRAIL inhibited the growth of NB4 and Jurkat cells in vitro in a dose-and time-dependent manner,but the effect of TRAIL on Jurkat cells was stronger than that on NB4 cells.However, the growth of K562 was not inhibited. Flow cytometry analysis revealed that DR4,DR5 and DcR1 were expressed higher in NB4 and K562 cells, but the levels of DR4 and DcR1 were very low in K562 cells.DR5 was expressed in Jurakat cells with low level. No DcR2 was detected on the surface of all the three cell lines.Conclusion NB4 cell line is moderately sensitive to TRAIL,and K562 cell line is resistant to TRAIL.The sensitivity of NB4 cells to TRAIL may be associated with the expression of DcR1, but the sensitivity of K562 cells have nothing to do with the expression of TRAIL receptors.