A crude extract was prepared from the fruiting body of Lepista flaccid, an edible mushroom and endoglucanase activity of the extract was increased 14-fold with ammonium sulphate precipitation. Maximum enzyme activity was seen at pH 4.0 and 50 degrees C when carboxymethylcellulose was used as a substrate. K-0.5 and V-max values of the partially purified endoglucanase were 7.7 mg/ml and 25 +/- 0.9 U/mg protein, respectively. The enzyme was quite stable over a broad range of pH (2.0-9.0) at 4 degrees C. When it was incubated at temperatures between 20 degrees C and 60 degrees C for 12 h, it conserved much of its original activity (over 40%). The activity of the enzyme increased by 234 +/- 3.6% in the presence of 1 mM Mn2+. The endoglucanase was inhibited by EDTA, PMSF, beta-ME and DDT. In conclusion, pH and thermal stability of the L. flaccida endoglucanase could make it useful for industrial purposes. (C) 2010 Elsevier Ltd. All rights reserved.