Fourteen reef-building coral species of Anthozoa and Hydrozoa classes, collected in various regions of the Indo-Pacific, were analyzed for fatty acid composition by gas-liquid chromatography. Total lipids of the corals had the same set of fatty acids. The main fatty acids were 16:0, 18:0, 18:l(n-g), 20:4(n-6), 20:5(n-3) and 22:6(n-3), but some coral families had significant levels of characteristic fatty acids. Poc~lloporidae -20:3(n-6), Acroporidae -18:3(n-6), 18:4(n-3) and 22:4(n-6); Poritidae -18.3(n-61, Milleporidae -22:4(n-6), 22:5(n-6) and 22:6(n-3). Related species of Pocilloporidae from Vietnam and Seychelles differed greatly in their content of saturated a c~d s -50 to 60 D/a and 30 %, respectively. As shown for Stylophora pistillata, the depth of the habitat affects the degree of fatty acid unsaturation and (n-3)/(n-6) ratio of neutral lipids, but does not affect phospholipid fatty acids. A possible role of A5-and A4-desaturases in determining fatty acid pool formation in reefbuilding corals is discussed with reference to their nutritional characteristics.