Endoglucanase production by Bacillus circulans LS9 was increased through culture medium optimization, leading to 3,6 U/ml titers. Endoglucanase excretion, which is associated with other polysaccharide degrading activities, is not sporulation associated and not totally repressed by glucose or cellobiose. Moreover, the optimum pH for endoglucanase activity is close to pH 7.