We analyse the diet and prey selection of puma Puma concolor and describe opportunistically the diet of jaguar Panthera onca in montane forest in the Sierra Nanchititla Natural Park, central Mexico. We analysed prey selection in relation to energy content and population abundance, inferred through camera trapping. Analysis of 209 puma scats showed that their main prey was nine-banded armadillo Dasypus novemcinctus followed by white-nosed coati Nasua narica and white-tailed deer Odocoileus virginianus. Pumas did not take prey in proportion to their relative abundance, but selected energetically profitable prey such as nine-banded armadillo, which formed the bulk of their diet. In 13 scats of jaguar, nine-banded armadillo was also the most important prey followed by domestic goat Capra hircus. We discuss the implications for management of predators and prey.