Six new polyoxygenated briarane-type diterpenoids, briaexcavatins Q–T (1–4) and robustolides J (5) and K (6), were isolated from a cultured octocoral Briareum excavatum and a sea whip gorgonian coral Ellisella robusta, respectively. The structures of briaranes 1–6 were established by spectroscopic methods. Briarane 3 exhibited weak cytotoxicity toward CCRF-CEM tumor cells and briaranes 5 and 6 displayed inhibitory effects on superoxide anion generation by human neutrophils.