Recovery of dilignols-trilignols fraction was studied in this work. Solvent resistant ultrafiltration and nanofiltration membranes were used to fractionate ethanol and ethanol/dichloromethane extracts obtained from straw degraded by Pleurotus ostreatus. It was shown that ultrafiltration is very effective in removing solid suspensions. Permeates from ultrafiltration were processed by nanofiltration membranes with MWCO = 1000, 350, 250, and 200 Da, in a screening study aimed to find the best option for the separation and concentration of the dilignols-trilignols fraction. It was demonstrated that it is possible to separate and concentrate the lignin degradation products with molecular mass of 200-390 Da in an integrated UF/NF process with good yields (60-85%) and concentrating the product tenfold. (C) 2012 Elsevier B.V. All rights reserved.