Only relatively few cases of dental abnormalities in wild ruminants have thus far been described in the paleopathological literature. This study reports a case of cementoblastoma, a benign odontogenic tumor of ectomesenchymal origin, in a red deer (Cervus elaphus) from the Late Pleistocene of Rochedane, a prehistoric site in the French Jura. The tumor was attached to the root of a heavily worn loose left maxillary third molar. CT imaging revealed several radiolucent (former soft tissue) spaces of varying shape and size within the mineralized tumorous mass. Light microscopic analysis and backscattered electron imaging in the SEM showed that the process of dental wear had reached the tumor and that the tooth and the attached tumor had undergone considerable microbial diagenesis. This is the first case of cementoblastoma described in a prehistoric animal and also the first report of this type of odontogenic tumor in a deer.