of the plant wall cell, as cellulose, hemicellulose, lignin and pectins are degraded by enzymatic systems produced by a wide variety of saprophytic and phythopathogenic microorganisms, including bacteria and fungi. The aim of this work was to produce avicelase, carboxymethylcellulase, xylanase and pectinase from the exo-1 mutantNeurospora crassa, FGSC 2256 and thewild typeNeurospora crassa, FGSC 424. The exo-1 mutant has a pleiotropic mutation which confers derepression of alpha-amylase, glucoamylase, betafructofuranosidase, and trehalase, as previously documented. This mutation appears to also affect the composition of the cell wall, since segregants resulting from the backcross of exo-1 to the wild-type strain from which it derived are altered in the ratio of galactosamine to glucosamine in the cell wall. Conidial cell walls of exo-1 mutant exhibit a marked decrease in the amount of galactosamine. In this work, increased levels (approximately sixfold) of pectinasewere found in conidia of exo-1 as comparedwith those of thewild type andalso thepolysaccharide-degrading activitieswere preferentially induced and secreted by the exo-1mutant compared with wild type cells, in the presence of inducers. Then, in culture media supplemented with 1% avicel from the exo-1 mutant were observed higher levels of avicelase (10.6-fold), carboxymethylcellulase (8.92-fold) and xylanase (4.74-fold) than in the wild type. Galactose was better inducer of pectinase than pectin and the exo1 mutant produced three-fold more polygalacturonase than the wild type. Constitutive levels of polygalacturonase and cellulolytic enzymes were detected in medium devoid of carbon source. This results show the importance of composition of the fungal cell wall in the regulation and secretion of industrial enzymes with application in the biomass treatment and biofuel biotechnology. Support: FAPESP and CNPq