Hyperplastic connective tissue formation in the posterior part of the temporomandibular joint glenoid fossa has previously been described in autopsy specimens. The frequency of such hyperplastic tissue formation in patients with long-standing temporomandibular joint pain was studied in 103 joints from 80 patients by means of double-contrast arthrotomography. Five joints in four patients (5%) demonstrated hyperplastic tissue formation; in four cases this was associated with permanently displaced and deformed disks. All five joints were refractory to nonsurgical treatment. Surgically extirpated hyperplastic tissue and disk attachments contained nerve fibers and thickened adventitia of vessels, resulting in narrowed or obliterated lumina, extravasated erythrocytes, and fibrinlike deposits. The synovial membrane showed fibrinoid necrosis or was lost. The pain reaction in temporomandibular joints with hyperplastic soft-tissue formation may be released by compression or tension of nerves, breaking down products from blood or tissue ischemia. Contrast filling of both joint spaces, combined with tomography, was required for detection of the hyperplastic tissue formation.