Acidic polysaccharide fractions from soy-bean hulls have been examined by partial hydrolysis or partial acetolysis. Oligosaccharides, which have been characterised, include 2-O-α-L-fucopyranosyl-D-xylose, 2-O-β-D-galacto-pyranosyl-D-xylose, 4-O-β-D-galactopyranosyl-D-galactose and its polymer homologues, 4-O-(α-D-galactopyranosyluronic acid)-D-galacturonic acid and the polymer-homologous trisaccharide, 2-O-(α-D-galactopyrano-syluronic acid)-L-rhamnose, higher oligosaccharides containing galacturonic acid and rhamnose residues, and small amounts of glucuronic acid-containing aldobiouronic acids. The results of partial hydrolysis and of methylation of some of the fractions indicate that the acidic polysaccharides comprise a group of structurally related polysaccharides of the pectic acid type.