Cassia auriculata Linn. seeds yielded a water-soluble polysaccharide on acid hydrolysis as D-galactose and D-mannose in 1:3 molar ratio. Upon periodate oxidation of seeds polysaccharide with sodium metaperiodate, it consumed 1.25 moles of periodate with simultaneous liberation of 0.35 moles of formic acid per mole of anhydro hexose sugar unit after 50 hours. On the basis of methylation results, the proposed seeds polysaccharide structure of Cassia auriculata Linn. plant has been confirmed by periodate oxidation method.