BACKGROUND Malocclusion is one etiological factor of temporomandibular joint disorder (TMD). This study investigates the prevalence of TMD and the relationship between TMD and the type of occlusion. METHODS A sample of 923 children (463 girls and 460 boys, ages 7-12 years old) was grouped not only by chronological age but also by gender. The information was collected on functional occlusion (anterior and lateral sliding, interferences), dental wear, mandibular mobility (maximal opening, deflection, deviation), and temporomandibular joint and muscular pain recorded by palpation. RESULTS Headache was the only symptom of temporomandibular dysfunction (TMD) reported by the children. The results showed that one or more clinical signs were recorded in 25% of the subjects, most of which were mild in character. The prevalence increased during the developmental stages. Girls were in general more affected than boys. CONCLUSIONS In this study, many subjects with TMD had malocclusions. Early treatment may be important in the prevention of severe TMD. Significant associations were found between different signs, and TMD was associated with posterior crossbite, anterior open bite, Angle Class II and III malocclusions, and extreme maxillary overjet.