The Mexican gray wolf (Canis lupus baileyi) was extirpated from Arizona and New Mexico in the 1970s. In 1998, Mexican gray wolves were translocated into the east-central Arizona portion of the Blue Range Wolf Recovery Area. One measure of success of the translocation is the ability of the Mexican gray wolf to capture native prey. Our objectives were to determine diet of wolves during summers 2005 and 2006, and contrast diet in areas that were grazed by livestock seasonally to areas grazed annually. We collected scats, identified contents from hair and bone fragments, and estimated diet by calculating percentage biomass of prey consumed. Elk (Cervus elaphus) comprised 80.3% of diet of the Mexican gray wolf. Other prey included domestic cattle (16.8%), deer (Odocoileus; <1%), squirrels (<1%), other rodents (2%), and lagomorphs (<1%). In areas of year-around grazing, 21% more livestock were consumed, compared to areas grazed seasonally.