The composition of Hwoangbaec-tang has been traditionally used in Korea to treat cancer. Hwoangbaec-tang I is the water extracts prepared from Angelica dahurica, Fritillariae verticillata, Ailanthus altissima, Viscum coloratun, Scutellaria Radix, Ginseng Radix, Astragalus membranaceus, and Glycyrrhizae Radix. Hwoangbaec-tang II also is the water extracts prepared from Ginseng Radix, Astragalus membranaceus, and Glycyrrhizae Radix. The anti-leukemic effects of human promyelocytic leukaemia (HL-60 cells) by Hwoangbaec-tang I or II was accessed by propidium iodide staining flow cytometric analysis, and apoptosis-inducing activity was further confirmed by a nuclear morphological change, a ladder pattern of DNA fragmentation, and an activation of caspase-3 and 9. Hwoangbaec-tang I was found to induce the apoptosis of HL-60 cells via caspase-3 and 9 pathway. In the other side, Hwoangbaec-tang II was found to inhibit the growth of HL-60 cells by inducing these cells to differentiate toward granulocytes. These results indicate that the different anti-leukemic effects of Hwoangbaec-tang in HL-60 cells can be induce the apoptosis or differnetiation of HL-60 cells in Hwoangbaec-tang composition dependent manner.