Imazapic has shown potential to control invasive weeds, such as cheatgrass (Bromus tectorum L.), during ecological restoration, but effects on non-target native plants are poorly known. In a replicated field experiment, as part of restoration for Gunnison sage-grouse (Centrocercus minimus) in Colorado, imazapic was applied in the fall at a high rate (175 g/ha) to control cheatgrass in mowed Wyoming big sagebrush (Artemisia tridentata Nutt. ssp. wyomingensis Beetle & Young). Cheatgrass was reduced, but only by 67%, and non-native forbs were reduced by 80% by the following summer. However, native forbs also declined (by 84%). Two native grasses declined, but others were not affected. Damage to native forbs would likely be detrimental to sage-grouse and other wildlife if it occurred over large areas. Perhaps application of imazapic just to cheatgrass plants or patches and application earlier in restoration would allow control with less adverse effects on native forbs.