In the present study, we used greenhouse experiments to show the ability of Trichoderma harzianum BI to: (1) suppress the root knot nematode, Meloidogyne javanica infection and nematode egg hatching on tomato plant; and (2) laboratory experiments to monitor the induction of some resistance-related enzymes in plants and production of extracellular chitinase using colloidal chitin as the substrate.