Chalcones have been identified as interesting compounds with cytotoxic and tumor reducing properties. In the present study, the biological activity of synthetic chalcones on, myeloid leukemic. cells was, investigated. Human myeloid HL-60 leukemia cells were exposed to 1-20 muM chemicals for 0-96 h. The viability of the cells was measured using trypan blue dye exclusion method. 4,4'-Dihydroxy chalcone (RVC-588) was selected for further experiments to determine characteristics of cytotoxicity among other compounds.