Purpose: To determine the effect of fresh soy milk and its compounds (coumestrol, daidzein and genistein) on apoptosis in human leukemic cells and peripheral blood mononuclear cells (PBMC). Methods: The apoptotic effect of fresh soy milk and its compounds on human leukemic cells (K562, Jurkat, U937) and PBMC was determined by flow cytometry. The PBMC from healthy donors were isolated by conducting density gradient centrifugation principle. Lymphoprep and cytotoxicity of the compounds was evaluated by 3-(4,5- ‘;1dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) MTT) assay. Results: PBMC treatment of daidzein and genistein had a significantly higher half-maximal inhibitory concentration (IC50) value (p < 0.01) and (p < 0.0001), compared to the leukemia cells. In addition, soy milk had a significantly higher IC50 value (p < 0.05) in PBMC than the leukemia cells. Coumestrol induced a significantly increased apoptotic cells in K562, U937 cells (p < 0.01) and Jurkat cells (p < 0.05). However, daidzein only increased apoptosis (p < 0.05) in K562 and U937. Genistein reported a significantly increased apoptotic cell in K562, Jurkat (p < 0.01) and U937 cells (p < 0.001). Nonetheless, in PBMC, significant apoptosis by the compounds did not occur. However, only soy milk induced a significantly increased apoptosis in PBMC (p < 0.05). Conclusion: The findings indicate that coumestrol, daidzein, genistein and soy milk inhibits the viability of leukemia cells by apoptosis induction, but they are non-toxic toward normal cells. Therefore, the results suggest that the compound alone, and thus, soy milk might have a therapeutic effect in leukemia.