The effects of mannan oligosaccharides preparation (MO), as elicitor, and ferulic acid inducer for enhancement in laccases production in liquid cultures of three strains of basidiomycetes, Pycnoporus sanguineus, Coriolopsis polyzona and Pleurotus ostreatus was studied using a full factorial 3 2 experimental design. MO, either individually or combined with ferulic acid, enhanced laccases levels in the three different strains of the white-rot fungi. The enhancement of laccases production was species specific with the highest increase in liquid cultures of P. sanguineus (88-fold) followed C, by P ostreatus (3-fold) and C. polyzona (2-fold). Separate additions of 75 mg/1 of MO to the cultures of P. sanguineus and P. ostreatus caused the increase while a combined addition of 150 mg/1 of MO and 1 mM ferulic acid resulted in the optimal production of laccases in the cultures of C. polyzona. (c) 2006 Elsevier Inc. All rights reserved.