Aspergillus vesicolor mycelial cells were covalently immobilized on a glutaraldehyde-epsilon-amino-caproyl-NH2-Separon, and the constitutively-produced beta-glucanase system and some properties of purified beta-1,3-glucanase were compared with those of freely suspended cells. It was found that the mycelial immobilization modulates the composition of the beta-glucanase system as well as stimulates the export of a functionally different beta-1,3-glucanase.