An obligate parasitic bacterium of nematode, Pasteuria penetrans 98-35 (PP), isolated from oriental melon greenhouse soil in Korea, was evaluated against root-knot nematode , Meloidogyne arenaria (MA), in tomato (Lytepersicon escuzentum Mill. vw. Youngkwang) and oriental melon (Cucumis metro L. vu. Eunchun) . Pot experiments were conducted by planting the tomato seedlings in a medium inoculated with 5,000 MA juveniles/pot (J2), J2+100,000 PP endospores/1 g medium, and J2+200,000 PP endespores/1 g medium. After 10 weeks from planting, root gall percentage in J2+100,000 and J2+200,000 PP endospores/1 g medium were significantly lower with 37.5% and 6.7%, respectively, compared with the J2 of 85%. In the second planting of tomatoes in the same pots , root gall numbers were significantly lower in PP treated pots representing 68.8 and 31.4/root in J2+100,000 and J2+200,000 PP endospores/1 g medium, respectively, compared with the J2 of 460.6/plant. In oriental melon experiment, numbers of root galls after 10 weeks from planting were significantly lower in J2+100,000 endospores/1 g medium with 32.5 compared with 64.1 and 87.5 in J2+100,000 endospores/1 g medium and the 12, respectively. However, there were no significant differences in plant growth characteristics among thulcorner treatments in the both crops