A beta-glucosidase (EC 3.2,1.21) was purified as an electrophoretically homogeneous protein from a solid culture of Aspergillus sojae. The molecular mass of the purified enzyme was estimated to be 250 kDa by gel filtration chromatography and 118 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The isoelectric point of the enzyme was 3,80. The maximum velocity of p-nitrophenyl beta-D-glucopyranoside degradation by the beta-glucosidase was attained at 60 degrees C and at pH 5.0. The purified enzyme was stable from pH 6.0 to 8.0, and up to 50 degrees C. The activity of the enzyme was significantly inhibited by Hg2+ and Cu2+, and stimulated by Mn2+ and Fe3+,The purified enzyme hydrolyzed beta-D-xylopgranosides as well as beta-D-glucopyranosides; the K-m and V-max values on p-nitrophenyl BD-glucopyranoside were 0.14mM and 16.7 mu mol/min/mg protein, and on p-nitrophenyl beta-D-xylopyranoside 0.51mM and 12,2 mu mol/min/mg protein, respectively.