Digestible dry matter [DDM], digestible energy and metabolizable energy were measured for 3 diets fed to a 9 mo. old red fox (V. vulpes). The 3 diets selected were white-tailed deer (Odocoileus virginianus), snowshoe hare (Lepus americanus) and an apple-deer mixture. The diets were evaluated in 3 continuous 10 day series. White-tailed deer had the highest energy content and snowshoe hare the lowest. On a dry wt basis, consumption was highest for the hare diet and lowest for the apple-deer diet. DDM was highest for the deer diet (96.9%), whereas the hare and apple-deer diets were less digested (77.9 and 82.2% DDM, respectively). The digestible energies for the deer, hare and apple mixture were 97.0, 85.4 and 85.7%, respectively. Respective metabolizable energies were 87.9, 76.1 and 83.4% for these diets. In all cases deer was the most highly utilized, and hare had the lowest utilization at each level. Metabolizable energy could not be calculated for an apple diet. This was due to a decrease in the protein of apple-deer diet as compared to the deer diet, resulting in less total energy given off in urine. Combining the results reported here with BMR and diet composition may allow estimates of the potential impact of a fox population on its prey.