ABSTRACT Soft corals have been proved to be a rich source of bioactive natural products. This research revealed isolation and structure elucidation of bioactive natural products in the Taiwanese soft coral Junceella juncea. The acetone extract of J. juncea collected in Ken-ting exhibited cytotoxicity against tumor cells. Bioassay- directed fractionation of the EtOAc-layer has resulted in the isolation of five new briaranes, designated juncenolides A-E (1-5) along with a known compound, junceellolide C (6). The structures of compounds 1-6 were determined by the physical methods such as mp¡BIR¡Bmass¡Band optical rotation, and 1D¡B2D NMR spectral analysis, as well as the data reported of the related compounds in publications. In addition, the relative configuration of compound 1 was further confirmed by X-ray single crystal analysis. The basic structures of compounds 1-6 contain a 6/10-membered ring linked with a £^-lactone at C-7/8 and an epoxy group at C-11/20 position. Compound 1 had a chlorine atom at C-6 position with two acetoxyl and an isobutyl groups at C-2, 9, 14 positions. Compounds 2-5 had a cis-cis conjugated double bonds system at C-3, 4, 5, 6 positions, Among them , compound 2 had four acetoxyl groups at C-2, 9, 13, 14 positions, while compounds 3 and 4 had five acetoxyl groups at C-2, 9, 12, 13, 14 positions. In particular, compound 4 had a methoxyl group at C-16 position, which was first found in the briarane-type natural products. Compound 5 had three acetyl and a 3-methylbutyl groups at C-2, 9, 13, 14 positions. In a preliminary pharmacological aporach (cytotoxicity), compound 1 exhibited moderate cytotoxicity against human colon adenocarcinoma (DLD) and oral epidermoid carcinoma (KB-16) cells at a concentration of 3.4 and 5.9 £gg/mL, respectively.