The author examined bone changes from 1274 poly tomographic images of 182 temporomandibular joints which showed symptoms of temporomandibular disorder and the following results were obtained; 1. The number of temporomandibular joints which showed bone changes were 64 (35.2％) among 182 joints. 2. The age and sex distribution of 64 joints which had bone changes showed the prevalence of female (90.6％) and third decade (25.0％) followed by fourth (21.2％) and second decade (17.2％). 3. The 252 images which showed bone changes consisted of 56 images from lateral side (22.2％). 118 images from center (46.8％) and 78 images from medial side (30.9％). 4. The most frequently observed bone changes were flattening (22.7％) followed by sclerosis (19.3％) and cortical unsharpness (19.3％)