The authors examined arthrotomographies of 89 patients (96 joints) with closed lock of the temporomandibular joint to clarify the frequency of disk deformity correlated with disk perforation, bone change and patients' age. The disk configurations were divided into 3 types, those were type-1-elongated and preserved shape of the disk, 39 joints, type 2-folded disk, 11 joints, and type 3-massed disk, 46 joints. The frequency of disk deformity was 66.7% (64 joints). The numbers of disk perforation, (and bone change) in each type were type 1-2 (5) joints, type 2-1 (1) joint, and type 3-11 (13) joints. The average ages of each type were type 1-28.1 years, type-2-27.2 years, and type 3-40.1 years. These results indicate that high percentage of disk deformations exist in the closed lock patients with degenerative changes of the soft and hard parts of the temporomandibular joint.