Shiraia bambusicola is a saprophytic Ascomycetes grown on bamboo in south China.Two new heteropolysaocharidea,named SB1 and SB2,had been- isolated from the mycelium.Both SBl and SB2 were homogeneous.Ths component sugars of SB1 were D-glo,D-gal and L-ara in the molar ratio of 0.37:1:0.07 and SB2 were D-glo,D-gal,D-man and L-ara in the molar ratio of 0.25: 1:0.47: 0.12.The MW of SB1 and SB2 were 6900 and 25000,respectively.Methylation,periodate oxidation,Smith degradation and graded hydrolysis studies suggested that SB1 and SB2 possessed branch structure.The repeating units of SB1 contained 8 types of linkage.The main linkages were composed of 1,3- and 1,3,6- linked galaotopyranoayl residues,1,4- and 1,3,6-linked galaotopyranosyl residues and a few 1,6- linked,galaotofuranosyl residues.The repeating units of SB2 contained 7 types of linkage.The main linkages were composed of 1,2- and 1,3,6- linked mannopyranosyl residues,1,4- and 1,3,6- linked galaotopyranosyl residues and a few 1,6-linked galaotofuranosyl residues.