Purpose: Several clinical studies suggest that psychologic factors may play an important role in the etiology and maintenance of temporomandibular disorder (TMD) signs and symptoms. The goal of this study was to verify the prevalence of anxiety and depression in adolescents, and their relationship with signs and symptoms of TMD. Materials and Methods: The sample comprised 217 nonpatient adolescents between 12 and 18 years of age. The subjective symptoms and clinical signs of TMD were evaluated, respectively, using a self-report questionnaire and the Craniomandibular Index (CMI, which has 2 subscales), the Dysfunction Index, and the Palpation Index. The Hospital Anxiety and Depression Scale (HADS), a 14-item self-administered rating scale that was developed specifically to identify anxiety and depression in nonpsychiatric medical outpatients, assessed levels of anxiety and depression. Results: In the total sample, anxiety and depression were present in 16.58% and 26.71% of subjects, respectively, including all levels of HADS. The results showed that there were positive correlations between CMI and Palpation Index and anxiety (HADSa) (P .01) but not with depression (HADSd). An association between the number of TMD subjective symptoms and HADSa/HADSd was found (P .01). Conclusion: Anxiety and depression, although of mild intensity, are common in adolescents. In this study both HADSa and HADSd were associated with an increasing number of TMD subjective symptoms. However, only anxiety was correlated with clinical signs of TMD (CMI), primarily muscle tenderness (Palpation Index).