The actinomycete, Streptomyces hygroscopicus was shown Lo be capable of producing extracellular cellulase and cell associated beta-glucosidase activity during growth on cellulose containing media. Cell homogenates were shown to contain a beta-glucosidase fraction which was stable for up to 24h. at 30-degrees-C and had half-lives of 480min. and 220 min. at 40 and 50-degrees-C, respectively. The enzyme fraction was also shown to be optimally active at pH 4.0 suggesting that it might represent a suitable supplement for fungal cellulase systems, deficient in beta-glucosidase activity.