One new cembrane diterpene, 2R,7R,8R-dihydroxydeepoxysarcophine (1), together with three known compounds, 7 alpha,8 beta-dihydroxydecpoxysarcophine (2), 7 beta-acetoxy-8 alpha-hydroxydeepoxysarcophine (3), and sarcophine (4), have been isolated from the Red Sea soft coral Sarcophyton glaucum. Their structures were determined using 1D and 2D NMR spectroscopy. 7 beta-Acetoxy-8 alpha-hydroxydeepoxysarcophine (3) exhibits cytotoxic activity against HepG2, HCT-116, and HeLa cells with IC(50) values of 3.6, 2.3, and 6.7 mu g/mL, respectively.