The author analysed the bone changes, the positional relationships between condylar head and articular fossa, and the interrelationship between the bone changes and the abnormal position of condylar head, from 1,036 radiographs of 259 patients with temporomandibular joint arthrosis, which were obtained by the oblique-lateral transcranial projection and orthopantomograms. The results were as follows: 1. Among the radiographic bone changes of the temporomandibular joint arthrosis, deformity was 36.90%(217 case), sclerosis 34.18% (20 cases), errosive chang 25.85% (152 cases) and marginal proliferation 3.06% (18 cases) respectively. 2. In the positional changes between condylar head and articular fossa, the downward positioning of condylar head in centric occlusion was most frequent(36.90%), of which frequency was signifiantly higher than forward positioning (11.22%) and backward positioning(4.76%) in same condition. Also, radiographs showed that the enlargement of articular space showed higher frequency than its narrowing. In the opening position of mouth, the restricted movement of condylar head within articular fossa was most frequent(35.03%). The forward positioning and the downward positioning was 15.65% and 9.52% respectively. Also, radiographs revealed that the incomplete movement or no positional change of condylar head was most frequent. 3. In the interrelationship between bone changes and abnormal position of condylar head, deformity was 42.79% in the cases of downward positioning of condylar head in centric occlusion and 37.50% in those of normal positioning of condylar head in same condition. This revealed that deformity was most frequent bone change in above condylar positionings. However, erossive change was 34.62% in the cases of downward positioning of condylar head in centric occlusion and 33.33% in those of forward positioning. In opening position of condylar head, and deformity in the cases of normal positioning, forward positioning and downward positioning of condylar head was 38.38%, 36.96% and 44.64% respectively. 4. Bone changes of condylar head was 47.11%, articular eminence 41.50% and articular fossa 11.39% respectively. This revealed that the frequencies of bone changes. were higher in the projected portion of bony structures of temporomandibular joint than their depressed portions. On the otherhand, in the bone changes of condylar head, deformity was 59.57% which was the most frequent. In the bone changes of articular eminence and articular fossa, however, sclersis was 41.39% and 65.67% respectively, which was the most frequent in those portions.