Ambystoma altamiranoi is an endangered endemic salamander found in the Transvolcanic Belt of Mexico. Unfortunately, relatively little is known about its ecology. Here we report on the diet of larval A. altamiranoi from a population in Llano de los Axolotes, Sierra de las Cruces, State of México, Mexico. Empty stomachs were found in 13.3% of individuals. Ostracods and gastropods dominated the diet of A. altamiranoi, together accounting for 89.9% of prey items consumed. The remainder of the diet consisted primarily of insects. Our observations suggest that the diet of A. altamiranoi is relatively narrow and that resources may be limited (relatively high frequency of empty stomachs), suggesting that factors that could impact the availability of ostracods and gastropods might have serious consequences for these endangered salamanders.