ObjectiveTo investigate the bioactive constituents of coral Scleronephthya sp. collected from the South China Sea. MethodsThe compounds were isolated and purified using repeated column chromatographies on Sephadex LH20, normal and reversedphase silica gels, and RPHPLC. The structures of the compounds were elucidated based on the detailed spectroscopic analysis in combination with reported data. The in vitro antimicrobial activity of these compounds were assessed by an agar diffusion test. Results and conclusion Three 5α,8αepidioxysterols, two alkyl glycerol ethers and 1,2Oalkyl glycerol were isolated from Scleronephthya sp.；these compounds displayed different levels of antifungal and antibacterial activities in bioassay in vitro. Compound 5 inhibited the growth of Gramnegative bacterium Escherichia coli and the Grampositive bacterium Bacillus megaterium. Compound 6 showed marked antifungal activity against Microbotryum violaceum. Compounds 14 demonstrated a weak antimicrobial activity.