The carbohydrate metabolism of the agents of psittacosis (6 BC), meningopneumonitis, feline pneumonitis, mouse pneumonitis, trachoma (TE-55), and inclusion blennorrhea was studied using glucose labeled with C 14 in carbon positions 1, 6, random, and 3,4. Although no O 2 consumption could be demonstrated, it was clearly shown that CO 2 was produced from at least two carbon atoms, including carbon 1, but not carbon 6. The activities of the six strains were remarkably similar to each other and could be better correlated with the total number of particles than with the number of particles infectious for the chick embryo. Significant amounts of radioactive pyruvate were also produced from all four preparations of glucose. Control preparations of uninoculated yolk sacs exhibited metabolic activities smaller than those of the microorganisms by one to two orders of magnitude. The above-described experiments add appreciably to the growing evidence that the agents of the psittacosis-trachoma group more closely resemble bacteria than viruses.