A clinical and radiographic survey was conducted with 39 patients (39 joints) who had undergone discectomy of the temporomandibular joint between 1965 and 1974 and whose cases had been followed for an average of 20 years after surgery. There were 3 males and 36 females, ranging in age from 16 to 70 years (average, 33 years) at the time of surgery. Masticatory disorders, arthralgia, limitation of condylar movement, and trismus were the chief symptoms, and clicking and crepitus were present in six and two patients, respectively. Plain radiography showed osteoarthritic changes such as osteophyte formation or lipping on the condyles of eight joints. Arthrography showed disc perforations and peridiscal adhesions in 27 patients, and displacement of the disc in eight. All discs were totally extirpated and condylar shaves were performed in eight patients who had disorders such as osteophytes, exostoses, or lipping on the condyles. In follow-up examinations, 37 patients had no pain, but mild arthralgia was noted occasionally in two patients. Postoperatively, no patients experienced subjective masticatory disorders; 38 patients were able to open their mouth more than 35 mm, and crepitus was heard in only two joints. Plain radiography showed bony changes on the condyles and eminences of all joints. From this long-term follow-up study it is concluded that discectomy is a useful operation for treatment of severe disc pathology causing pain and functional disturbance in the temporomandibular joint.