Based on the study of 25 cases, the authors recall the frequency and pathogeny of these lesions, specifying the surgical technique and presenting their results. The risks of this surgery lie in the ever possible impairment of the facial nerve and labyrinthization on treble frequencies (2 cases). The incidents are tympanic perforation (1 case) and the opening of the temporomandibular joint. It is not always possible to preserve the skin of the external auditory canal. It can be reconstructed by a free (3 cases) or pedicle (3 cases) graft of more simply in case of small loss of substance by a temporal fascia graft.