Introduction: The conventional technique for cochlear implant is through mastoidectomy and posterior timpanotomy. Objective: This paper describes the technique presently used in the ENT Department of University of São Paulo Medical School, which is the result of implementations in more than 50 patients. Methods: First a wide mastoidectomy is performed with posterior tympanotomy to allow the access to the middle ear. A cochleostomy is than performed anterior and superior to the round window, so that the electrodes can be introduced in the scala tympani.