The operation may be performed either (_a_) through the external meatus or (_b_) by reflecting the auricle forward by a post-auricular incision. =Through the external meatus.= This method is only indicated if the exostosis is situated at the entrance of the meatus and is pedunculated. A general anæsthetic is given, the patient being in the recumbent position. The surgeon works by reflected light. After the ear has been thoroughly cleansed a large-sized aural speculum is inserted into the meatus and the outlines of the exostosis are defined with a probe. A small gouge or chisel is used. It is inserted into the meatus in such a fashion that its point presses between the pedicle of the exostosis and the wall of the bony meatus. With successive sharp taps of the mallet, the gouge is made to cut through the pedicle, care being taken that the instrument is not driven in too deeply, on to the tympanic membrane. The growth, which can now be felt to be movable within the meatus, can usually be removed by grasping it between the blades of forceps, or can be expelled by syringing the ear. After its removal the auditory canal should be plugged for a few minutes with a solution of cocaine and adrenalin chloride. This checks all hæmorrhage, and at the same time enables the surgeon to get a good view of the deeper parts to see if further growths are situated more deeply within the meatus. Such growths, provided they are pedunculated and do not abut on the tympanic membrane, can sometimes also be removed by the same method; much depends on their shape and situation. If sessile or too deeply placed, the operation may have to be completed by reflecting forward the auricle. Before terminating the operation a clear view of the tympanic membrane should always be obtained. The meatus is finally syringed out with a 1 in 5,000 aqueous solution of biniodide of mercury and dried, a strip of sterilized gauze being inserted into the auditory canal. A simple dressing is then applied to the side of the head. _Other methods of operation through the external meatus._ (_a_) Perforation of the exostosis, or enlargement of the small passage existing between multiple exostoses, by means of the burr. Although successful results have been recorded, this method is not advised, as cicatricial tissue almost invariably causes closure of the opening made. To keep the opening patent it is necessary to insert a small lead or silver canula, frequently a source of great discomfort. (_b_) If the exostosis has a very fine pedicle, it may be possible to nip through its base with a pair of forceps, but it is not so sure a method as the employment of a gouge and mallet. (_c_) Such methods as attempts to destroy the growth by means of the galvano-cautery or by the pressure of laminaria tents should be avoided; they are useless and unsurgical. =By reflecting the auricle forward.= This is indicated if the exostoses are multiple, have a broad base, and are deeply situated.