Introduction: Like any other synovial joint, the temporomandibular joint (TMJ) can be involved in juvenile idiopathic arthritis. TMJ can be affected unilaterally and bilaterally at the beginning or during the course of the disease, and can also often be affected by the first and only affected joint. Objective: To describe the clinical case of the patient diagnosed with temporomandibular disorder due to juvenile idiopathic arthritis, emphasizing the need for professionals to address the temporomandibular joint even in the absence of clinical symptoms. Case Report: Child, male, 10 years old, diagnosed with juvenile idiopathic arthritis, complained of pain in the region of the temporomandibular joint and limited mouth opening. During the clinical examination, he did not report pain on accessory muscles palpation, masticatory and cervical muscles. However, during palpation of the temporomandibular joint, it was found the presence of bilateral pain and decreased mouth opening, the maximum forced opening, with pain, marked 18 mm. The examination by cone beam computed tomography was requested and images out of the normal range were observed in both heads of the mandible, with the left side being more affected, showing flattening and erosion. After examining the exams, a diagnosis suggestive of type 3 internal derangement was reached. Thus, the proposed treatment consisted of using an occlusal splint and physiotherapeutic follow-up to reduce painful symptoms and increase mouth opening. After two weeks, an increase of 4 mm in the mouth opening was noted, with no effort or pain. After 3 months of proservation, an opening of 32 mm was observed with a stable patient regarding the initial complaints. Conclusion: The approach of the temporomandibular joint is extremely important in patients with juvenile idiopathic arthritis, since this association occurs quietly in most cases. Early recognition is essential in favor of favorable conducts and prognoses.