The periodontal membrane of European hamster maxillary incisors showed histologic changes consisting of an irregularly orientated, less vascularized connective tissue which included abundant cementicle‐like structures. The changes were multilocal and bilateral, growing towards the alveolar bone (Grade 1), causing atrophy of the alveolar bone due to compression (Grade 2) and reaching the periosteal membranes (Grade 3). In a few animals, the lesions were seen after one year. They were seen in 80% of hamsters more than 2 years old. Carcinogenic exposure did not alter the latency and incidence of the alterations. The lesions were thought to be a spontaneously occurring disease representing a nodular cemento‐fibrous dysplasia of the periodontium. As, morphologically, no exact attribution to other odontogenic or mesenchymal growth could be made, the entity of this periodontal lesion was considered. Although the changes observed in the periodontal membrane of the maxillary incisors of the European hamster were not exactly comparable to odontogenic cemental lesions in man, they may serve as a model to further clarify the nature of fibro‐osseous le