Abstract: Oil seed radish (Raphanus sativus cv. common L.) has been used for plant-parasitic nematodes as an green manure and trap crops. This study was conducted to determine and compare the effects of root exudates of oilseed radish and susceptible tomato (Lycopersicon esculentum L. variety Rutgers) on Meloidogyne hapla greenhouse populations from Manhattan (MH), New York (NY) and Michigan (MI) in order to understand the way of effect of OSRC (Oil seed radish). In a laboratory, 3 mL exudates of OSRC, tomato and same amount of water introduced with 1000 eggs of each nematode population that come from greenhouse mass culture separately. Hatched second stage juveniles were counted for 8 days and exudates were renewed with stock solution every day. Although tomato exudates increased hatched juvenile number but there is no statistically difference between OSRC and tomato exudates. Also all different M. hapla populations showed same responses to every exudate. As a result it may said that, OSRC does not effect M. hapla population by influencing egg hatching but, it may effect infection and/or reproduction level of nematodes.