Trichoderma harzianum (Rifai) isolate was collected from the Rhizosphere soil of Tomato field and tested for their antagonistic activity against Fusarium oxysporum f. sp. lycopersici ((SACC.) Synder and Hans) causing Fusarium wilt of Tomato. The antagonistic fungus was very effective in inhibiting the mycelial growth of the pathogen in Dual culture. The antagonistic fungus produced lytic enzyme (Chitinase) which was found to inhibit the growth of the pathogen in vitro. In green house experiments, the antagonist Trichoderma harzianum was effective in the suppression of the pathogen Fusarium causing wilt in Tomato plants. Seed treatment with Trichoderma harzianum broth recorded an increase in the seed vigour index by 69.02 % over the control also promoting the Plant Growth (PGPF).