Xyloglucan is one of the major components in the primary cell wall of higher plants. It is intimately associated with cellulose chains, forming the load-bearing network of the cell wall. Enzymatic degradation of the xyloglucan polymer by xyloglucanases could potentially improve the overall hydrolysis of lignocellulosic substrates by enabling cellulases to hydrolyze the cellulose polymer more efficiently due to the increased surface area. In order to evaluate the role of xyloglucan in the enzymatic hydrolysis of lignocelluloses, II different pretreated cellulosic substrates were hydrolyzed using different combinations of purified cellobiohydrolases I and II, endoglucanase II, xyloglucanases of Trichoderma reesei and Aspergillus P-glucosidase. Xyloglucanase activity improved the total hydrolysis of lignocellulosic substrates in general. These results indicate that this enzyme can be used to enhance total hydrolysis, especially in cases when pretreatment of the lignocellulosic substrate is not optimal. (C) 2008 Elsevier Inc. All rights reserved.