Asterriquinone (ARQ, 1a) is an antitumor metabolite of Aspergillus terreus IFO 6123. To gain insight into the structure-activity relationships of ARQ, a series of chemically modified derivatives (1-6), the ARQ analogues (b-e) and the 2, 5-dihydroxy-p-bezoquinone analogues (f-h), were prepared, and cytotoxic acitivity against mouse leukemia P388 cells investigated. Results indicated that : 1) at least one hydroxy group or acetoxy group in the p-benzoquinone moiety is important to exhibit cytotoxicity; 2) in the p-benzoquinone moiety, a single methoxy group and/or one aceotxy group substitution showed more potent cytotoxicity than when two hydroxy groups are substituted (1); 3) the indole ring is important for the cytotoxicity of ARQ analogues; 4) the 1, 1-dimethly-2-propenyl group in the indole ring is not important for the cytotoxic activity of ARQ.