In order to investigate the effects of rhGM-CSF on apoptosis of HL-60 cells induced with VP-16 treatment, HL-60 cells were first incubated with rhGM-CSF before they were treated with VP-16. The apoptosis processes and the changes in apoptosis related gene bcl-2 and fas expression were observed. The morphological and ultrastructural changes were observed under optics microscope and electromicroscope. DNA fragmentation were detected by agarose gel electrophoresis, the apoptotic rate, bcl-2 and fas expression with flow cytometry. Our results showed that rhGM-CSF inhibited the apoptosis of HL-60 cells induced with VP-16 treatment, which enhanced the down-regulation of bcl-2 expression, but inhibited the up-regulation of fas expression. So it suggested that rhGM-CSF can decrease the sensitivity of HL-60 cells to VP-16, probably by down-regulation of fas expression.