The extracellular polysaccharides produced by Cryptococcuslaurentii have been isolated and shown to consist of (A) an acidic polysaccharide containing D-mannose, D-xylose, and D-glucuronic acid; (B) a neutral polysaccharide containing D-glucose only.Preliminary structural studies on the acidic material suggest that it consists of a mannose-containing backbone with xylose and glucuronic acid as end groups, while the glucan contains 1 → 3, 1 → 4, 1 → 2, and (or) 1 → 6 linked residues.