This study was designed to determine the diets of four species of Sonoran Desert rodents (Dipodomys merriami, Perognathus ampins, Perognathus baileyi, and Perognathus intermedins) and compare the diets to available food resources. Items ingested and their relative frequencies were determined by microscopic examination of stomach contents. Contents of cheek pouches of these heteromyid rodents also were analyzed and the relative density of each item was calculated. Seeds, especially those of forbs were the primary food of all species, but insects were important in diets of D. merriami and P. intermedins. Green vegetation was eaten infrequently. Soil samples taken at the capture sites of the rodents were analyzed for seeds to determine their relative density. It was found that availability of resources generally determined the pattern of food utilization, but that the preferences of the various species determined the exact quantities used. Cheek pouch contents were found to be consistently different from stomach contents and poor indicators of how much and when specific items were ingested.