beta-1-3-Glucan synthase activity and its induction by olive mill wastewaters (OMW) was studied in ten fungal strains ( Auricularia auricula-judae, Lentinula edodes, Pleurotus eryngii, Stropharia aeruginosa, Agrocybe aegerita, P. pulmonarius, Armillaria mellea, P. ferulae, P. ostreatus, P. nebrodensis). A microtiter-based enzymatic assay on beta-1-3-glucan synthase activity was carried out on all mycelia growth both on the control medium and on OMW. Among the fungi assayed, L. edodes beta-1-3-glucan synthase was highly enhanced in OMW. The main components of OMW, i.e. phenols and lipids, were added separately to the control medium, to highlight the mechanism of L. edodes beta-1-3-glucan synthase induction. A Southern blot analysis and PCR with degenerated primers were carried out to detect the presence of fks1-like genes in these Basidiomycetes. The sequences obtained from the ten Basidiomycota were remarkably similar to fks1 from Filobasidiella neoformans. Spectrofluorimetric and RT-PCR analyses of beta-1-3-glucan synthase were performed on the mycelia of L. edodes. In this fungus, a strong stimulation of beta-1-3-glucan synthase mRNA and protein was recorded in the presence of OMW and phenols.