Nematicidal potential of some plant extracts were evaluated for the control efficacy of the northern root-knot nematode, Meloidogyne hapla on tomato (Lycopersicon esculentum) in pot. Tagetes patula, Zoysia japonica, Rhus sylvestris, R. chinensis, and Allium cepu were used. Leaf or root extracts were prepared at the rate of undiluted and diluted to 2, 4, 8, or 16 times with distilled water and treated simultaneously, ahead or later tomato planting. Pre-treatments of extracts were more effective than simultaneous or post-treatments, and the number of egg masses was different according to concentrations. M. hapla was less infected when the T. patula was planted at 15 days ahead tomato planting. Leaf or root extracts of T. patulu reduced damages of M. hapla significantly in all treatments. Leaf extract was more effective than root extract; the number of egg masses was 2.2 and 5.5 in 5-days pre-treatment of leaf or root extracts while 129.4 in control. In Z. japonica treatment, the number of egg masses was 87.2 in control, 21 in undiluted concentration of leaf extract and 28.4 in diluted concentration as 2 times. Leaf extracts of R. sylvestris, R. chinensis and A. cepa were also very effective against M. Izapla. The number of egg masses of M. hapla was 1.6, 1.6, and 6.2 in 5-days pre-treatments of R. sylvestris, R. chinensis and A. cepa, respectively while it was 193.6 in control. Less egg masses of M. hapla were detected in higher concentrations than in lower concentrations of all the plant extracts. Key Words - Meloidogyne hapla, Biological control, Egg masses, Tagetes patula,