Objective: To report the outcomes of patients that have undergone revision cochlear implant surgery for suspected device malfunction. Study Design: Retrospective case series. Setting: Academic medical center. Patients: Adult cochlear implant patients with devices that fail to lock or maintain a lock but are associated with troubling signs and symptoms. Intervention: Revision cochlear implant surgery. Main Outcome Measures: Demographics, presenting signs and symptoms, surgical findings, complications, audiologic performance and device analysis. Results: To date, 33 revision cochlear implant operations have been performed in 30 patients. Eight (24%) presented with a failure of the speech processor to lock with the internal device (i.e., hard failure). Twenty-five (76%) presented with either aversive auditory (n = 23 [92%]) or nonauditory (n = 21 [84%]) symptoms or performance-related issues (n = 16 [64%]) while maintaining a lock (i.e., suspected soft failure). Revision surgery resulted in resolution of the patient's presenting signs and symptoms in nearly 90% of cases and significant improvements in auditory performance. Perioperative complications were uncommon. Preoperative testing and device analysis frequently did not reveal the reason for presumed device malfunction. Conclusion: Revision cochlear implantation should be considered in patients significantly affected by intolerable auditory and/or nonauditory symptoms or when performance issues have been documented.