- OBJECTIVE: To identify the prevalence of new-onset balance symptoms in adult patients who have undergone cochlear implantation (CI). DESIGN: A retrospective, questionnaire-based prevalence study of 227 consecutive adults (age > 16 years) who have undergone CI. The control group comprised patients awaiting CI. SETTING: Tertiary hospital, Vancouver, British Columbia. METHODS: All patients implanted at the study centre were contacted. A questionnaire regarding their past medical history and the presence and character of pre- and post-CI dizziness was completed. Patients were divided into four groups based on the presence or absence of their symptoms in relation to the time of implantation. Patients with vestibular symptoms further completed the Dizziness Handicap Inventory (DHI). MAIN OUTCOME MEASURES: Incidence of balance symptoms pre- and post-CI and associated DHI scores. RESULTS: One hundred ten of 227 patients (48%) responded. Fifty-three (48.3%) had dizziness prior to CI and 64 patients (58.2%) postimplantation. Forty-one patients (37.3%) noted new onset of balance symptoms or a change in their symptoms post-CI. The onset was immediate (within 1 week post-CI) in the majority of this group (63.4%). DHI scores were generally low across all groups. CONCLUSIONS: Delayed- and late-onset new balance-related symptoms occur in approximately 5 and 9% of CI patients, respectively, and the self-perceived handicapping effects of these symptoms may be greater compared with patients with symptoms prior to implantation.