Cochlear implants have dramatically changed the treatment and prognosis for patients with profound sensorineural hearing loss. Deaf adults and children can be successfully (re)integrated into the hearing world through a multidisciplinary approach involving otolaryngologists, audiologists, and speech/language pathologists. As the technology of the cochlear prosthesis advances, the candidacy for these devices continues to broaden. This review addresses the basic technology, candidacy criteria, and important issues in the fields of adult and pediatric cochlear implantation. Cost utility and future directions in the treatment of the profoundly hearing impaired are discussed.