Melamine-formaldehyde-resin-based wood-polymer composites were prepared with cane bagasse pith as a filler. The filler was treated with 1% maleic, phthalic, and succinic anhydrides in xylene separately. The treatment was carried out for different time periods. The effects of the treatment were determined from the acid and ester values of the filler material after every treatment time. Therefore, treated and untreated filler materials (60 wt %) were separately employed for the composite preparation with melamine-formaldehyde as a matrix (40%). Various mechanical tests of the prepared composites showed the effect of the treatment. The mechanical properties were improved by the anhydride treatments up to particular period of the treatment. Each of the anhydrides had a profound effect on the peculiar mechanical properties. Of the three anhydrides, succinic anhydride and phthalic anhydride appeared to be better compatibilizers for a treatment period of 2 h at a concentration of 1% in xylene. The inconsistency in the acid values and mechanical properties beyond 2 h of treatment with the anhydrides was due to chemisorption and desorption phenomena. (C) 2003 Wiley Periodicals, Inc.