Kangaroo rats have been described as primarily granivorous; however, they also consume green vegetation. We investigated selectivity of grasses by kangaroo rats (Dipodomys ordii and D. merriami) presented with four common perennial grass species from the Jornada Basin in the Chihuahuan Desert. All grass species offered were utilized, and there were differences in utilization. Our results suggest that water content may underlie these differences, although other factors are not excluded. Merrian's kangaroo rats removed more tillers from each tussock of grass than Ord's kangaroo rat. Ord's kangaroo rat may select grasses with higher water content per tiller.