Five Caulerpa species available in Western Australia have been investigated for the presence of terpenoid metabolites. A new bicyclic diterpene, containing a labd-7-ene skeleton and a 1,4-diacetoxybutadiene moiety, has been isolated from C. trifaria. C. brownii, C. flexilis, C. peltata and C. racemosa lacked significant quantities of terpenes and only caulerpin could be isolated from C. peltata and C. racemosa.