Abstract Chromatographic purification of a methinol extract of Formosan soft coral Sinularia numerosa (collected in Green Island) led to the isolation of two norcembrane norditerpenoids, (1R*,5S*,8R*,10S*,11R*)¡V11¡Vhydroxy¡V1¡Visopropenyl¡V8¡Vmethyl¡V3,6¡Vdioxo¡V5,8¡Vepoxy¡Vcyclotetradec¡V12¡Vene¡V10,12¡Ðcarbolactone (19) and (1R*,5S*,8R*,10S*,11S*)¡V11¡Vhydroxy¡V1¡Visopropenyl¡V8¡Vmethyl¡V3,6¡Vdioxo¡V5,8¡Vepoxy¡Vcyclotetradec¡V12¡Vene¡V10,12¡Ðcarbolactone (33). Purification of a chloroform extract of the Formosan plant Aglaia elliptifolia (collected in Green Island) resulted in the isolation of six compounds, 3-hydroxy-5,7¡¦,4¡¦-trimethoxyflavone (295), dehydrodorin (135), piriferine (133), foveolin B (218), cyclopenta[b]benzofuran ligan derivative (186) and a new compound (298). Compounds 295,135,133 and 218 are known compounds; compounds 186 and 298 are new compounds. In cytotoxicity assays, compounds from Sinulari numerosa, 19 and 33 exhibited significant cytotoxicities against four cancer cell lines. However, just one compound, 186 from Aglaia elliptifolia , showed significant cytotoxicity; the other compounds were not cytotoxic (ED50 ¡Ù4£gg/mL).