The purpose of this study was to determine the influence of growth conditions and medium composition on the production ofchitinase by Streptomyces sp. (strain S242). Production of chitinase by strain S242 was detected on colloidal chitin agar (CCA) medium after 8 days of incubation at 28 degrees C resulting in a clear zone 10 mm around the colony. Chitinase activity was assayed as the amount of N-acetylglucosamine released in micromol/ml/min using the dinitrosalicylic acid assay method. The crude enzyme had maximum activity (0.162 U ml/l) after 4 days of incubation at pH 7 and 30 degrees C when the broth medium was supplemented with 1.6% of colloidal chitin. However, enzyme activity was strongly decreased at 40 degrees C and extreme acidic and alkaline pH values. SDS-PAGE and zymogram analysis revealed six distinctive bands that range from 39 to 97 kDa with chitinolytic activity. The findings of this investigation create a possibility for the use of the organism in the commercial production of chitinase. In addition, it can be a source of DNA for cloning the chitinase gene(s) to generate phytopathogen resistant transgenic plants.