AbstractThis chapter focuses on some of the biotechnological applications of the genus Trichoderma in agriculture and the environment. The Trichoderma-pathogen interactions (competition, antibiosis and mycoparasitism) are discussed. Some strategies used to obtain new and better antagonistic strains of Trichoderma with enhanced properties are explored. In addition, the Trichoderma-plant interaction like stimulation of plant defence mechanisms, plant root colonization and biofertilization, are discussed. Finally, the heterologous expression of Trichoderma genes, and the potential of Trichoderma species in bioremediation are covered.