Chromatographic separation of methylene chloride extracts of Formosan soft coral Lemnalia cervicorni May (collected at Green Island off Taiwan) led to the isolation of four ylangene sesquiterpenoids, GN40-29 (1), GN40-79 (3), GN40-169 (4), and GN40-173 (5). Acetylation of GN40-29 (1) gave a derivative GN40-29a (2). Compounds 3-5 were new compounds. Compound 1 showed cytotoxicity against HT-29 cell, while compound 5 was cytotoxic to P-388 cells. The methylene chloride extracts of Formosan soft coral Dendronephthya spinifera Holm (collected at Green Island off Taiwan) were found to contain a new cadinene sesquiterpene, GN43-4 (6).