­^¤åºK­n The marine sponge Dysidea avara was collected along south seashore area of Kenting. Fractionation of the EtOH extract by using silica gel column chromatografphy and HPLC yielded avarol¡]1¡^ and avarone¡]2¡^. The structure elucidation of 1 and 2 was achieved by NMR¡]300 MHz¡^, EIMS, FABMS, UV, IR and specific rotation. In order to study the structure and activity relationship, compound 1 was acylated to yield a series of avarol derivaties¡]14 ~ 20¡^. In addition, three compounds¡]22 ~ 24¡^ were prepared from methylhydroxyquinone via acylation. Derivatives 14 ~ 20 and 22 ~ 24 were confirmed by spectral methods including NMR, MS, UV and IR as 2¡¦,5¡¦-O -dibenzoylavarol¡]14¡^¡B2¡¦,5¡¦-O-¡ep-chlorobenzoyl¡favarol¡]15¡^¡B2¡¦,5¡¦-O-dicinnamoyl -avarol¡]16¡^¡B2¡¦,5¡¦-O-¡ep-bromobenzoyl¡favarol¡]17¡^¡B2¡¦,5¡¦-O -dioctanoylavarol¡]18¡^¡B2¡¦,5¡¦-O-¡ep-florobenzoyl¡favarol¡]19¡^¡BDiacetylavarol¡]20¡^¡Bmethylhydroxyquinone¡]22¡^¡B2¡¦,5¡¦-O-¡ep-chlorobenzoyl¡fmethylhydroxyquinone¡]23¡^¡Bdiacetylmethylhydroxyquinone¡]24¡^. All of these compounds were send to National Health Research Institute and National Research Institute of Chinese Medicine for antitumor and antiviral tests in vitro. The investigation of their structure and activity relationship is now in progress.