Intractable slipping at the temporomandibular articulation may be due either to a lesion of the interarticular fibrocartilage—corresponding to a lesion of the internal meniscus of the knee—or to an actual dislocation of the condyle which slips forward over the eminentia articularis. The former group can be cured by the simple removal of the meniscus. For curing the latter group, a new operation is described, consisting in the construction of a bone block just anterior to the eminentia articularis. Four cases of cure are cited,—one of the first group, three of the second.