The lipid content of Diadumene luciae (Aiptasia igenea) reached about 1.8% w/w of the fresh material. GLC analysis of the unsaponifiable matters revealed that squalene was the major saturated hydrocarbon followed by n-hexacosane, C-30, n-octacosane, n-docosane and n-tetracosane. Cholesterol was the major sterol followed by ergosterol and B-sitosterol. Analysis of the saponifiable matter revealed that oleic acid constituted the major fatty acid followed by linoleic, arachidonic, stearic, arachidic, palmitic, margarie and myristoleic.