RS1 and RS2 are two genetic stocks that have low saturated fatty acid (SFA) contents. In this two-year study, we report on the inheritance of palmitic and stearic acids of RS1 and RS2 in the F1 and F2 generations of crosses with HA 382, an inbred line with a fatty acid composition similar to many commercial sunflower hybrids. The expression of the reduced palmitic and stearic acid traits is most important in the F2 generation because it is the F2 seed that is harvested by the farmer, sold, and crushed for the oil. Our experiments showed that the F2 seed of reciprocal crosses of RS1 or RS2 with HA 382 was intermediate in SFA content between the two hybrid parents. The inheritance and expression of the reduced palmitic and stearic acid traits of RS1 and RS2 were controlled by more than one gene. In addition, there were significant relative changes in palmitic and stearic acid contents between the growing seasons of 2002 and 2003, suggesting that environment played a significant role in the relative proportions of these fatty acids. The total SFA content was also influ enced by environment, producing opposite effects with RS1 (higher total SFA in 2003) and RS2 (lower total SFA in 2003). The data demonstrate that it will be necessary to incorporate the reduced SFA trait into both parents of a hybrid in order to achieve the lowest concentration of SFAs in the F2 seed.