Resistance to a peanut-parasitic population of Meloidogyne javanica and an undescribed Meloidogyne sp. in peanut breeding lines selected for resistance to M. arenaria was examined in greenhouse tests. The interspecific hybrid TxAG-7 was resistant to reproduction of M. arenaria, M. javanica, and Meloidogyne sp. An M. arenaria-resistant selection from the second backcross (BC) of TxAG-7 to the susceptible cultivar Florunner also was resistant to M. javanica but appeared to be segregating for resistance to the Meloidogyne sp. When reproduction of M. javanica and M. arenaria were compared on five BC4F3 peanut breeding lines, each derived from M. arenaria-susceptible BC4F2 individuals, all five lines segregated for resistance to M. javanica, whereas four of the lines appeared to be susceptible to M. arenaria. These data indicate that several peanut lines selected for resistance to M. arenaria also contain genes for resistance to populations of M. javanica and the undescribed Meloidogyne sp. that are parasitic on peanut. Further, differences in segregation patterns suggest that resistance to each Meloidogyne sp. is conditioned by different genes. Key words: Arachis hypogaea, genetics, Meloidogyne arenaria, Meloidogyne javanica, Meloidogyne sp., nematode, peanut, resistance, root-knot nematode.