A pectic polysaccharide from soy was degraded by a crude extracellular preparation of Aspergillus aculeatus. Besides monomeric sugars, an unknown oligosaccharide was produced, which was purified and identified as the dimer beta-Xyl(p)-(1,3)-GalA(p). The enzyme responsible for the release of this dimer was purified and characterized as an exogalacturonase, which was not hindered by side-chains of xylose.