SUMMARY: The ribonucleic acid fraction of Micrococcus pyogenes var. aureus (strain Duncan), separated by the method of Schmidt & Thannhauser (1945), contains organic phosphate in excess of that which can be accounted for by a polynucleotide nucleic acid structure. This ‘excess phosphate’ can be separated from the other phospho-compounds after fractional extraction of M. pyogenes in dilute acid or in dilute alkali. Four polyolphosphate compounds occur in the extracts. The main components are α-and β-glycerophosphate, the two other polyolphosphates (giving water-insoluble barium salts; separable chromatographically) occurring in smaller amount. The yields of glycerophosphate show that at least 75% of the ‘excess phosphate’ is present in an easily hydrolysed glyccrophospho-compound which may also be the origin of the unidentified polyolphosphates. The glycerophospho-compound of M. pyogenes accounts for more than one-quarter of the total organic phosphate of the organism. The presence of ‘excess phosphate’ in a number of Gram-positive organisms suggests that a glycerophospho-compound similar to that of M. pyogenes may be of general occurrence in Gram-positive bacteria and in yeasts.