Abstract Two new briarane-related diterpenoids, designated as briaexcavatins G (1) and H (2), were isolated from the octocoral Briareum excavatum, collected off southern Taiwan coast. The structures, including the absolute stereochemistry of these two new metabolites, were established by spectroscopy and chemical conversion. The configuration of briarane 2 was further supported by molecular mechanics calculations. Briarane 1 showed weak inhibitory effects on human neutrophil elastase release.