Selection for ability of soybean cyst nematode (SCN), Heterodera glycines, to reproduce on soybeans with different sources of resistance divides some SCN race 4 field populations into two distinct subpopulations. These subpopulations reproduce well on 'Bedford' and plant introduction (PI) 88788 or PI 89772 and PI 90763 but not on both pairs of soybean lines. The ability of these subpopulations to reproduce on the four soybean lines was reversed by changing the soybean line used as a host during a second cycle of selection. When SCN populations previously selected for reproduction on Bedford and PI 88788 were selected for their ability to reproduce on D72-8927 and J74-88, the ability of these populations to reproduce on Bedford and PI 88788 decreased significantly and their ability to reproduce on PI 89772 and PI 90763 increased significantly. Conversely, when SCN populations, previously selected for reproduction on P189772 and P190763, were selected for their ability to reproduce on Bedford, the reproduction of these populations on Bedford increased significantly and reproduction on PI 89772 and PI 90763 decreased significantly. Selection for ability of a SCN race 4 field population to reproduce on soybean lines derived from SCN race 4 resistant PIs resulted in the same division of the field population into two distinct subpopulations. These data substantiate earlier proposals to rotate cultivars with different genes for SCN resistance as a means of managing SCN populations.