Background This study was carried out to investigate the antifungal activity of chitinase produced by Streptomyces species isolated from grassland soils against selected pathogenic fungi, namely: Magnaporthe oryzae, Fusarium graminearum, Rhizoctonia solani, Puccinia species and Botyrtis cinerea. Chitinase produced by Streptomyces albus was purified consecutively with dialysis, gel filtration and ion- exchange chromatography, the test isolate can be exploited for large scale production of chitinase. Results Seven Streptomyces species (Streptomyces rimosus, S. albus, S. riseoflavus, S. fumosus, S. spiralis, S. aureofaciens and S. flavogriseus) isolated from three different grassland soils were screened based on the morphology and their ability to produce chitinase. S. rimosus, S. fumosus, S. albus and S. flavogriseus were able to produce chitinase, although the enzyme chitinase was found to be higher in Streptomyces albus. The effect of environmental factors were determined on Streptomyces albus being the best chitinolytic producing isolate. Temperature of 30οC was favourable for Streptomyces albus and pH 6.0 was a growth factor for maximum chitinase production. The activity of the enzyme was stimulated by the addition of metal ions like Mn2+, K+, Na+, Mg+, Fe2+, Ca2+ but Zn2+ inhibited chitinase activity. Chitinase activity was favoured by maltose as carbon source and NH4 (SO4)2 as nitrogen source. Culture filtrate of Streptomyces albus was able to inhibit the growth of all the selected pathogenic fungi namely Magnaporthe oryzae, Fusarium graminearum, Rhizoctonia solani, Puccinia species and Botyrtis cinerea whereas Streptomyces rimosus has the least inhibitory activity. Conclusions Streptomyces albus has the highest ability to produce chitinase which can act as antifungal for degradation of the cell wall of many phytopathogenic fungi.