One new (1) together with four known sterols (2 - 5) and a sesquiterpene (6) were isolated from a polar extract of the Red Sea soft coral Lobophytum crassum. The compounds were identified as 24-methylenecholest-5-ene-lα,3β,1lα-triol 1-acetate (1), 24-methylenecholest-5-ene-la,3β,llα-triol (2), 24- methylenecholest-5-ene-3β-ol (3), 24-methylenecholestane-la,3β,5α,6β,I la-pentol (4), 24-methylenecholestane-3β,5α,6β-triol (5) and alismoxide (6) based on extensive NMR analysis. The cytotoxicity of compounds 1 - 6 was evaluated in vitro using three human cancer cell lines viz., HepG2, Hep-2 and HCT-I 16. Compound 1 showed selective cytotoxic activity against HepG2, while 3 exhibited cytotoxicity against all tested cell lines.