The Ethiopian wolf (Canis simensis) is a rare and endangered carnivore found in only a few mountain ranges of the Ethiopian highlands. We studied its diet and feeding behavior in Bale Mountains National Park, Ethiopia, from 1988 through 1992. Observations of foraging behavior (n = 380) and scat analysis (n = 689) suggested that the Ethiopian wolf specializes in eating rodents. Rodents accounted for 96% of the prey occurrences and 97% volume in the droppings. The giant molerat (Tachyoryctes macrocephalus) was the main food item, followed in importance by three species of rats (Arvicanthis blicki, Lophuromys melanonyx, and Otomys typus). Ethiopian wolves foraged solitarily throughout the day, but occasionally small packs (≤6) hunted hares, young antelopes, and sheep. During food-choice experiments, wolves significantly preferred Tachyoryctes to Arvicanthis and Lophuromys, Arvicanthis to Lophuromys, and either of them to Stenocephalemys, which was invariably discarded. Lepus starcki was preferred to any of the species of rats. The contribution of different species of prey to the diet of the Ethiopian wolf correlated with abundance of prey.