Scleroglucan is a polysaccharide produced industrially by the fungus Sclerotium rolfsii. Aromatic carbamate derivatives of scleroglucan have been prepared via the reaction of phenyl and tolyl isocyanates on the hydroxyl groups of the polymer chain. The reaction conditions have been determined in order to obtain the fully substituted polymer while conserving as much as possible the initial chain length. The reaction in pyridine at 80 degrees C of a large exess of isocyanate (three times the stoechiometric amount) yields the higher degree of substitution (DS) and the higher intrinsic viscosity. These new polymers have been characterized by elemental microanalysis, spectroscopic methods (IR, H-1-, and C-13-NMR) and thermal analysis. They are found to be soluble in organic solvents and soften between 200 and 225 degrees C, and are thermally unstable above this temperature.