Seedlings of TP-135, an interspecific hybrid derived from four Arachis spp. and resistant to Meloidogyne arenaria race 1, and the susceptible cultivar Tamnut 74 were inoculated with 2,500 freshly hatched juveniles of M. arenaria. Plants were harvested at 7, 14, 21, and 35 days after inoculation (DAI) and the roots treated with acid fuchsin to stain infecting nematodes. Adult females with eggs were detected in roots of Tamnut 74 at 21 DAI, producing 1,395 eggs/g roots at 35 DAI. Most nematodes remained as second-stage juveniles and no nematode was observed to develop beyond the third or fourth juvenile stage in roots of TP-135 by 35 DAI. In other experiments, seedlings of Tamnut 74 and root cuttings of TP-135 were each inoculated separately with 3,000 eggs of 10 geographically diverse populations of M. arenaria race 1. All populations of the nematode had greater (P = 0.01) reproduction on Tamnut 74 than on TP-135. Based on these data, we conclude that although the mechanism of resistance in TP-135 to M. arenaria is most similar to that of the wild species A. cardenasii, it is not identical to that of any of the nematode-resistant parental species. Furthermore, we believe that the resistance will be effective against a range of populations of the nematode.