Total carbon in 19 species of marine organisms and mixed collections was analyzed by combustion in an induction furnace and hy subsequent measurement of evolved carbon dioxide in a gas burette. A system for trapping unwanted combustion products is described. Carbonate carbon was analyzed by treating samples with acid and measuring evolved carbon dioxide. Carbon concentrations were 6.6-46.8% of dry weight and 20.6-57.0% of organic weight. Cnidaria and ctenophores had the lowest carbon concentrations in organic matter.