The most common genes for semidwarf habit in modern wheat (Triticum aestivum L.) cultivars are found at the Rht-B1 and Rht-D1 loci on chromosomes 4B and 4D, respectively. An alternative gene for semidwarf habit, Rht8, has shown potential as a replacement for Rht-B1b and Rht-D1b in some environments. The objective of the present study was to assess the impact of the height-reducing gene Rht8 relative to Rht-B1b and Rht-D1b on performance of spring wheat in Montana and Washington environments characterized by terminal drought stress. Evaluation of near-isogenic lines developed in four genetic backgrounds showed that Rht-B1b, Rht-D1b, and Rht8 caused height reduction of 19, 20, and 6.5%, respectively, relative to wild-type near-isogenic lines over 12 environments. An increase in grain yield was associated with reduced height for lines containing Rht-B1b and Rht-D1b based on means over the four genetic backgrounds and 10 environments. Height reduction and yield increase associated with Rht-B1b and Rht-D1b were significant in most environments. Lines with Rht8 yielded less than wild-type based on means over environments and in 3 of 10 individual environments. Reduced height lines with Rht-B1b and Rht-D1b tended to have a higher harvest index and more seed per spike than wild-type lines and reduced height lines with Rht8. In sum, our results suggest that Rht-B1b and Rht-D1b are superior to Rht8 as a source for height reduction for spring wheat in the tested environments.