Many sagebrush-grass ranges have been seeded to crested wheatgrass [Agropyron desertorum (Fischer ex Link) Shultes]. These ranges are generally nutritionally inadequate for sheep (Ovis aries L.), except for short grazing periods in the spring and fall. To increase production and diversity, particularly crude protein for late-season grazing, fourwing saltbush [Atriplex canescens (Pursch.) Nutt.] was planted in an existing stand of crested wheatgrass. Quantification of sheep forage preferences on these improved ranges aids in determining the length of the grazing season and the extent to which shrubs provide the supplemental nutrition required. This seasonal grazing study was conducted on a characteristic wheatgrass-saltbush, mixed-range pasture to determine sheep acceptance of fourwing saltbush when crested wheatgrass was the alternative available forage. Sheep preferences for grass and shrub in spring and winter were similar, averaging 84 percent grass and 16 percent shrub. Summer dietary preferences ranged from 69 percent to 93 percent grass and 7 percent to 31 percent shrub. Preference for fourwing saltbush was consistently lower than crested wheatgrass in all seasons. Sufficient amounts of the mixed pasture were grazed to reduce the need for supplemental feed, when compared to crested wheatgrass monoculture. The results of these grazing trials suggest fourwing saltbush can be useful in improving pasture nutrition for sheep in different grazing seasons.