The cytotoxicities of 2 derivatives of artemisinin B and 2 derivatives of artemisic acid (designated as Compound A, B, C, and D) were investigated, using trypan blue dye exclusion test and colony-forming units assay. At the concentration of 5 micrograms.ml-1, the inhibition rates of these 4 compounds against murine leukemia cell line P388 were > 85%. When tested against human hepatoma cell line SMMC-7721 at 25 micrograms.ml-1, the inhibition rates of Compound A, B, C, and D were found to be 92.3%, 96.9%, 84%, and 82.1%, respectively, and 27%, 8%, 37.8%, 1.7% against normal human embryonic lung cell line WI-38, respectively. These 4 compounds all showed an inhibition rate of 100% against human gastric cancer cell line SGC-7901 at 50 micrograms.ml-1.