Abstract: Objective: To elucidate the effect of WT1 antisense oligonuclenotide （WT1 ASO） on apoptosis of leukemia cells and the role of WT1 gene in apoptosis of leukemia cells. Methods: K562, HL-60 cells were treated with WT1 ASO and VP-16. Then apoptosis was quantified by flow cytometric analysis assay. Results: WT1 ASO could induce apoptosis of k562 cells and the level of apoptosis increased markedly when combined with VP-16; WT1 ASO alone couldn’t induce apoptosis of HL-60 cells, but it could also increase the level of apoptosis of HL-60 cells when combined with VP-16. Conclusion: WT1 ASO could increase the susceptibility of leukemia cells to VP-16 and WT1 gene may play a role in apoptosis of leukemic cells and the rule in different cells is variable, which is influenced by the type of cell.