A 2-year cohort study of subjective symptoms of temporomandibular disorders (TMD) was performed. A total of 229 female adolescents, all 15 years of age, completed questionnaires and underwent dental examinations at baseline, 1- and 2-year follow-up surveys. The questionnaire included questions on typical TMD symptoms; i.e. temporomandibular joint (TMJ) noise, tiredness in jaws, pain on jaw movements, and difficulty in mouth opening. The relative risk was computed to determine the relationships of the baseline number of filled teeth (FT) and decayed, missing and filled teeth (DMFT) increment with the incidence of TMD. The percentage of subjects with one or more subjective symptoms at 17 years of age was 30.6%, significantly higher than the percentages at 15 (17.0%) and 16 (19.7%) years of age (P < 0.01). The symptom-emerging rate of TMJ noise during the 2-year period was 13.5%, which was the highest among the rates of possible subjective symptoms. Individuals with a 2-year increment in DMFT of > or =2 had a 2.14-times increased risk of experiencing mild symptoms, and individuals with baseline FT of > or =3 had 2.41-times increased risk of experiencing mild or severe subjective symptoms. The results of this study showed that TMD symptoms occurred in a relatively high percentage of female adolescents during the 2-year period and suggested that DMFT is one factor affecting the incidence of TMD.