The environmental infectivity caused by extreme use of chemical pesticides increased the interests in integrated pest management (IPM), where chemical pesticides are substituted by bio-pesticides to control plant pests and plant diseases. Genus Trichoderma has high ability to inhibit the growth of pathogenic fungus by secreting some enzymes. Trichoderma is an asexually reproducing filamentous fungus and a species aggregate. An effective biological control agent should be genetically stable, effective at low concentrations, easy to mass produce in culture on inexpensive media and be effective against a wide range of pathogens. The mechanisms of Trichoderma include direct competition with the target organism, antibiosis and parasitism of the target organism and induce resistance of the host plant. Therefore various agricultural by products were evaluated for mass production of Trichoderma species worldwide. Trichoderma haarzianum and T. viride was found suitable carrier materials to formulate various agro wastes. Biological control of plant pathogens through antagonists is a potential, ecofriendly and a sustainable approach apart them being a promising alternative to the use of chemicals. The major issue involved in mass production and utilization of biocontrol agents are selection of effective strains, development cost effective methods, for mass multiplication, effective methods for storage, consignment and its formulation. Abiotic factors also have a profound effect on the production and activities of enzymes and antibiotics associated with biocontrol by Trichoderma species.