Polysaccharides from thalli of Lasallia pustulata were extracted and characterized. The major fractions were characterized as pustulan, a β-glucan-chitin complex and a β-(1→3)-glucan. Other polysaccharides, which are minor components (less than 5%) solubilized with water from the alkali extracts of thalli, were shown to be galactomannans with a backbone of α-(l→6)- mannose partially substituted at positions 2 by galactofuranose and/or mannopyranose side chains of variable length. The relationship between these polysaccharides and those obtained by the same method from free-living fungi is discussed. The proportion or composition of the different polysaccharides studied was not affected by seasonal environmental conditions over a 2-year period.