Biological control is an effective, cheapest and safer strategy for management of soil dwelling plant pathogenic facultative parasitic fungi. The antagonistic ability of Trichoderma viride was determined by its physiological and biochemical state, so that change in physiological or genetical conditions could alter the antagonism and hence the ability was evaluated with interactions of different chemicals i.e. Ethyl methane sulphonate (EMS) and Hydroxyl amine (HA). The mutants obtained after chemical mutagenesis viz., TVME 3c, TVME 4c and TVMH4a found to possess highest Chitinase enzyme units/mg of protein i.e. 0.62, 0.63 and 0.61 respectively. The ability of high quantum of Chitinase with higher growth rate and sporulation was directly related to maximum inhibition ability of mutants against soil borne Plant pathogens like Rhizoctonia bataticola, Sclerotium rolfsii, and Fusarium spp. etc Hence, present study proved that mutagenesis is the efficient tool for improving bioefficiency of "Trichoderma viride", a biocontrol agent.