We studied the diets of desert mule deer (Odocoileus hemionus crooki Mearns) at 3 sites in Arizona and collated this information with that of previous diet studies of desert mule deer across their range in the United States. We documented 96 browse, 69 forb, 14 succulent, and 6 grass species that each constituted ≥ 1% of the diet during ≥ 1 season. The occurrence of individual plant species varied spatially and temporally. Changes in nutrient levels and climatic influence on relative availability and phenology of plant species likely influenced diet. Desert mule deer rely heavily on browse and forbes, which make up the majority of their diet (> 90%). Grasses and succulents were generally < 5% of the diet. Rangeland managers should strive to keep desert rangelands productive with a diversity of forage so animals have opportunities to exercise free choice of diet.