Abstract: Objective To explore the effect of DAPK overexpression on the biological behaviors and caspase-3 expression in HL-60 cells. Methods The expression of DAPK mRNA was detected by RT-PCR leukemia cell lines K562, Molt4, U937, and HL-60 cells. HL-60 cells were transfected by a eukaryotic expression vector pReceiver-M29-DAPK via LipofectamineTM 2000, and the impact of DAPK overexpression on cell apoptosis, cell cycle, cell differentiation and caspase-3 expression were analyzed. Results DAPK mRNA expression was positive in K562, Molt4 and U937 cells but negative in HL-60 cells. Significantly increased cell apoptosis was observed in pReceiver-M29-DAPK-transfected HL-60 cells by flow cytometry and Hoechst33342 staining. The cell cycle distribution and differentiation showed no significant changes after the transfection. The expression of caspase-3 was significantly increased in the cells after transfection. Conclusion DAPK gene overexpression promotes apoptosis of HL-60 cells without affecting the cell cycle and differentiation. Caspase-3 may be involved in the regulation of cell apoptosis.