1. 1. The biochemical composition of the body components of 24 species of echinoderms from McMurdo Sound, Antarctica were ascertained. These included 14 species of asteroids, three species of ophiuroids, three species of echinoids, three species of holothuroids, and one species of crinoid. 2. 2. Levels of ash (% dry wt) were high, reflecting large amounts of skeletal material in the asteroid body wall (31.3-80.3%), the ophiuroid disc (48.7-71.7%) and arms (56.8-72.7%), the echinoid test (79.5-80.5%), spines (88.6%) and lantern (79.3%), the holothuroid body wall (31.5-36.2%) and the crinoid cirri (83%), calyx (79%) and arms (63.5%). 3. 3. Levels of insoluble and soluble protein and lipid were high in the nutrient storage organ (pyloric cecum) of the asteroids and the gut of the ophiuroids. 4. 4. Analyses of the biochemical composition of the gonads of 16 echinoderm species reveal high levels of lipid and soluble and insoluble protein. In 88% of the species levels of lipid were higher in ovaries when compared to testes. 5. 5. Levels of carbohydrate were low in all body components. 6. 6. The biochemical composition of antarctic echinoderms is similar to species from other latitudes. High levels of lipid in ovaries of most antarctic echinoderms appear to be related to the preponderance of lecithotrophy at high latitudes. © 1987.