On the basis of a study of 180 wrist joints from 100 fresh cadavers of individuals ranging in age from fetuses to 94 years, it is concluded that the triangular fibro-cartilage is very liable to degenerative alterations associated with ageing. Degeneration begins in the third decade and progressively increases in frequency and severity in subsequent decades. The changes comprise reduced cellularity, loss of elastic fibres, mucoid degeneration of the ground substance, exposure of collagen fibres, fibrillation, erosion, ulceration, abnormal thinning, and, ultimately, disc perforation. The changes are more frequent and more intense on the ulnar surface, and they are always situated in the central part of the disc. It appears that disc perforation is degenerative and age-related: thus there were no perforations in the first two decades of life; in the third there were 7.6%, in the fourth 18.1%, in the fifth 40.0%, in the sixth 42.8%, and in the over sixties 53.1%. There was an associated pattern of degenerative changes in the wrist joint as a whole. The structures adjacent to the articular disc (discal surface of the ulnar head, discal part of the lunate) were much more often involved, and the changes were much more advanced, than on non-discal surfaces. It is argued that this is because of more intensive biomechanical forces, particularly rotational forces, in the disc compartment of the joint.