An extracellular polysaccharide has been recovered from the culture filtrate of the yeast Candida mucifera CCY 29-170-1 strain. Gel filtration of the crude polysaccharide yielded the representative galactomannan composed of (x/%) D-mannose (1.00), D-galactose (0.14), and covalently bound phosphate (7.6 mole %). On the basis of the results of methylation analysis, acetolysis, and 13C,1H, and 3P spectral measurements it was concluded that the phosphogalactomannan had an a-(1-*6)-D-mannopyranosyl backbone partially substituted on 0-2 with side chains of one, two, or three D-mannosyl units connected by a-(1->2) linkages. A small portion of the (1->3) linkages arised from the phosphorylated part of the polymer. D-Galactose was located exclusively at the nonreducing end of side chains. The phosphate was proved to be esterified to primary hydroxyl of side-chain D-mannosyl residues.