A -glucosidase from Armillaria mellea, an edible mushroom collected from Hdrnebi High Plateau (Trabzon, Turkey), was partially purified 41.1-fold by using ion-exchange chromatography and it was biochemically characterized. The enzyme exhibited maximum activity at pH 4.0 and 50 degrees C when p-nitrophenyl--D-glucopyranoside was used as a substrate. K-m and V-max values were calculated as 0.3 mM and 3.6 U/mg protein, respectively. A. mellea -glucosidase was quite stable in the range of pH 3.0-6.0 and 8.0 after 24 h of incubation at 4 degrees C. It was determined that the enzyme was extremely stable in the range of 20-50 degrees C after 1 h incubation. It was also determined that some metal ions and chemicals affected the enzyme activity in different ratios.