The purpose of the present study was to evaluate the relationship between psychological variables and the clinical diagnosis of temporomandbular disorders (TMD) in 12-year-old adolescents. TMD pain was assessed by RDC/TMD examination (Research Diagnostic Criteria for Temporomandibular Disorders) (Axis I and II). Five-hundred and fifty-eight subjects (330 girls and 228 boys) were examined. Bivariate analyses were performed using the Chi-square test (chi(2)). The logistic regression models were adjusted estimating the Odds Ratios (OR), their 95% confidence intervals (CI), and significance levels. Only 2.19% of the boys and 8.18% of the girls presented one of the Axis I categories. All variables from axis II were related to TMD diagnosis (p < 0.001). Gender was significantly related to TMD diagnosis (p = 0.0028). The risk of TMD incidence for girls was 3.5 times higher than that for boys (Odds Ratio = 3.52, Confidence Interval 1.31-9.43). The individuals who presented the variable 'characteristics of pain intensity' (CPI) higher than 0 had 31 times more risk of TMD incidence (Odds Ratio = 31.361, Confidence interval 6.01-163.5). We concluded that psychological variables and female gender are important risk indicators related to TMD incidence, even in adolescents.