SummaryLateral displacement of the mandible was induced experimentally in five adult male Rhesus monkeys. Following from 2½2 weeks to 19 months, the animals were sacrificed and examined histologically. Two of the monkeys received H3proline 4 months prior to sacrifice and radioautographs were prepared. The lateral displacement apparently caused great discomfort because the monkeys refused to eat and lost weight rapidly for a few months. After about 12 months, the monkeys could again eat their normal diet to the extent they started to gain weight slowly.The histological and radio‐autographic findings indicated almost no changes of the articular surfaces of the temporomandibular joints. However, extensive reorganization of the neck of the condyles was observed. Severe periodontal trauma and extensive movements of the teeth occurred in spite of the fact that the teeth in each jaw were splinted firmly togeth