Worldwide, Cyst Nematode (SCN: Heterodera glycines Ichinohe) is the most destructive pathogen on soybean [Glycine max (L.) Merr]. In the USA yield losses in 2003 are estimated to be nearly a billion dollars. Crop losses are primarily reduced by the use of resistant cultivars combined with crop rotations. Most resistant cultivars trace their resistance mainly to ‘Peking' and Plant Introduction (PI) 88788. Widespread use of these resistance sources has caused major shifts in nematode populations. Recently, cv. Hartwig was released which has comprehensive resistance to most nematode populations. A virulent nematode population LY1 was recently selected for reproduction on Hartwig. LY1 nematode population infects currently known sources of resistance except PI 567516C. The average numbers of females obtained on PI 567516C, and Hartwig, were 7 and 146, respectively. We determined the inheritance of resistance in soybean PI 567516C to LY1 nematodes. Soybean PI 567516C was crossed to the susceptible Hartwig and 105 F2:5 progenies were bioassayed for reaction to LY1. Resistance was conditioned by three major genes (Rhg rhg rhg). Chi-square value was 0.15 and probability was at 1% level. This information will be useful to soybean breeders for developing resistant cultivars to nematode population that infects Hartwig.