This book deals with research findings on a local isolate of Trichoderma harzianum and its nematicidal efficiency against root-knot nematodes. Among the thirteen native isolates of T. harzianum from Indian Type Culture Collection (ITCC) screened against Meloidogyne incognita, the cell-free extract (CFF) of isolate ITCC 6888 caused maximum mortality. Egg masses exposed to the CFF of ITCC 6888 caused significant (99.50%) egg hatch inhibition.The chloroform extract (CHLE) and butanol extract (BE) of 7day old culture of this isolate exhibited significant immobility and mortality in the juveniles till 1000ppm. GCMS analysis of these extracts gave thirteen compounds with butanol and seventeen compounds with chloroform.The isolate was rhizosphere competent as shown by bioefficacy trial in pots using unsterilized soil on tomato cv Pusa Ruby, with a significant reduction in root galls, egg mass production, eggs/egg mass and reproduction factor . T. harzianum ITCC 6888 holds potential as a biocontrol agent for M. incognita infecting vegetable crops.