Peanut root-knot nematode [Meloidogyne arenaria (Neal) Chitwood or Ma] is an increasingly common pest in the southern United States where crops such as peanut (Arachis hypogaea L.) and soybean [Glycine max (L.) Merr.] are grown. Four soybean plant introductions (PIs) are highly resistant to the peanut root-knot nematode. To determine if PI 594403, PI 594427C, and PI 594651B contain useful resistance genes from those previously characterized in PI 200538, populations developed from the PIs crossed to PI 200538 were tested for Ma response. Highly galled and highly resistant F2 plants were observed in each population. In two of the three populations, the highly galled F2 plants produced progeny that sustained significantly greater galling (P < 0.001) than those derived from highly resistant F2 plants. While the F2–derived progeny from the third population had more variability than was observed in the other crosses, progeny means of the lines were significantly different (P < 0.05). Individual F2–derived lines from highly galled or resistant F2 plants within all of the populations were significantly different from each other or from the parents. Thus, it is evident that these PIs likely contain unique resistance genes that, when combined with PI 200538–derived Ma resistance, could improve the level of Ma resistance in soybean cultivars.