Eighteen patients with an arthrographic diagnosis of temporomandibular joint disk displacement with reduction were treated with disk-repositioning onlays for 6 months. Arthrograms and tomograms were obtained before and after treatment. The arthrographic examination after treatment showed that the disk remained in the superior position in twelve but was again displaced in six patients. Three of the patients with disk displacement manifested no clinical signs, such as clicking or locking; two showed signs of locking; and one had reciprocal clicking. The patients with clicking or locking had more symptoms than the other patients. A retrospective analysis of the pretreatment arthrograms suggested that there could have been a medial component to the disk displacement in four of the six patients in whom the disk became displaced again during treatment. Medial disk displacements were not seen in the patients with a successful treatment outcome. This study suggests that recurrence of symptoms during treatment with disk-repositioning onlays is frequently associated with recurrent disk displacement. The study further suggests that medial displacement of the disk is more difficult to treat.