ObjectiveTo evaluate issues pertaining to cochlear implantation in patients with far advanced cochlear otosclerosis.Study DesignProspective cohort.SettingTertiary care referral center.PatientsEight adult patients (18 years of age or older) referred for management of profound hearing loss, the cause of which was determined to be otosclerosis.InterventionCochlear implantation with multichannel cochlear implant device.Main Outcome MeasuresBenefit from cochlear implant as measured by CID sentence scores, incidence and management of facial nerve stimulation, and technical issues pertaining to cochlear implantation in this patient population.ResultsAll patients demonstrated significant improvement in auditory function as measured by performance on CID sentence scores and ability to engage in telephone conversation. Facial nerve stimulation was present in two of eight patients and was managed with deactivation of the stimulating electrodes. Ossification in the basal turn of the cochlea, detected on preoperative computed tomography, necessitated placement of the electrode into the scala vestibuli in two patients and use of a thinner electrode (Nucleus 24) in a third patient.ConclusionPatients with profound hearing loss secondary to otosclerosis derive excellent benefits from cochlear implantation. Surgical implantation may be complicated by ossification of the cochlea, which can be detected on preoperative computed tomography. Electrode activation may be complicated by facial nerve stimulation, which can be addressed with programming strategies.