Temporomandibular joint dysfunction (TMD or TMJD), also known as temporomandibular joint dysfunction syndrome and temporomandibular disorder among others, is an umbrella term covering pain and dysfunction of the muscles of mastication (the muscles that move the jaw) and the temporomandibular joints (the joints which connect the mandible to the skull).

The most important feature is pain, followed by restricted mandibular movement, and noises from the temporomandibular joints (TMJ) during jaw movement.

Although TMD is not life-threatening, it can be detrimental to quality of life, because the symptoms can become chronic and difficult to manage. TMD has been considered as a type of musculoskeletal, neuromuscular, or a rheumatological disorder. TMD is the second most frequent cause of orofacial pain after dental pain (i.e. toothache).

TMD is a symptom complex rather than a single condition, and it is thought to be caused by multiple factors. Common treatments that are used include provision of occlusal splints, psychosocial interventions like cognitive behavioral therapy, medication (analgesics, anti-inflammatories, and steroids), arthroscopic joint lysis and lavage, and in extreme cases open joint surgery is indicated.