Tomato is one of the most important vegetables cultivated worldwide. Many pests and pathogens cause significant yield decline in growing fields. Root-knot nematodes are known to be devastating pathogens on tomato. Resistant varieties carrying Mi-1 gene have been effectively used to control of root-knot nematodes. However, the efficiency of Mi-1 has been especially restricted by virulent root-knot nematode populations in cultivated tomatoes. Therefore, new resistant genetic varieties are required in growing fields. Heat-stable wild tomato species are known to be resistance to Meloidogyne populations at high soil temperature. To our knowledge, there are limited studies on response of heat-stable materials to different virulent root knot nematode populations under 28 degrees C. In the present study, reactions of heat stable materials to different virulent isolates of M. incognita and M. javanica were investigated at 24 degrees C soil temperature. Results showed that these materials did not confer resistance against M. incognita and M. javanica virulent isolates. Therefore, searching of new genetic sources resistant to virulent root-knot nematodes is required for breeding program.