The polysaccharides, curdlan, starch and dextran were sulfated when heated in DMSO with sodium methyl sulfate and a catalytic amount of H2SO4 or with pyridinium methyl sulfate. Use of diminished pressure and anhydrous CaSO4 as a desiccant improved the degree of sulfation and recovery. Under conditions using sodium methyl sulfate, H2SO4 and CaSO4in vacuo, sulfation at O-6 was predominant in the cases of curdlan and starch, while sulfation at O-2 and O-3 was preferential in the case of dextran.