The growth of a virulent strain of Brucella abortus was stimulated by low concentrations of erythritol in a medium containing high concentrations of glucose and a wide range of amino acids. During growth in this medium the organisms used about 1 1/2 times their weight of erythritol as a carbon and energy source. The effect of erythritol was specific, since several C3 to C6 homologues had no growth-stimulating activity. Radiotracer studies snowed that a large proportion of the carbon of the erythritol was excreted as carbon dioxide; that remaining in the organisms was fairly uniformly distributed over all components. Erythritol and 2-deoxy-2-fluoro-DL-erythritol inhibited incorporation of glucose by the organism.