In the present study, intermaxillary fixation for a period of 1 or 2 weeks after excision of the articular disc was administered to maturing rats. After removal of the fixation, the animals were allowed unrestricted mandibular movement. Histological observations were made at the postoperative 3rd month in those rats which demonstrated normal occlusion. As a result, it was found that the normal articular disc did not regenerate. However, in the articular cavity, both connective tissue and articular disc-like structures were found. The major changes in the mandibular fossa were tylosis of the outer fibrous layer of the fossa and an accompanying shallowing tendency. The major changes in the condyle were tylosis and morphological deformation of the fibrous layer of the parietal region. The deformation was mainly manifested by a fan-shaped hypertrophy. In the cases in which neither connective tissue nor articular disc-like structures were present in the articular cavity, changes in the mandibular fossa and condyle were remarkable. The appearance of the articular disc-like structure was more frequent in cases with 2-week intermaxillary fixation than in those with 1-week fixation.