To analyze the outcome of a cochlear implant (CI) in patients with an inner ear malformation (IEM), to compare two commonly used classification systems for IEM, to identify the highest and lowest outcome performance of IEM, to determine the most frequent inner ear anomalies and a candidate for a cochlear implant with considerable improvement.Methods: A literature review including 64 previously published studies between the period 1987 to 2020. In addition, a retrospective study inclusive 16 cases with IEM having undergone 20 CI surgeries. Results:The review shows that 43 studies involving 1273 (19%) cases with IEM out of 6560 patients have demonstrated an improvement in auditory and speech performance after implantation. 30 studies involving a total of 551 cases with an isolated enlarged vestibular aqueduct (EVA) have reported considerable benefits in audiology and speech performance after CI. Several authors reported that patients who have mild anomalies have a better outcome than patients who have severe malformations. Clinical studies revealed that patients with IEM have seen improvements in the outcome of audiology and speech tests after implantation. Conclusion:CI is effective for patients who have severe to profound sensorineural hearing loss (SNHL) with inner ear anomalies despite other factors which may influence the outcome. The outcome of the minor IEM such as EVA is higher than the performance of the major anomalies like a common cavity (CC). The most frequent inner ear anomaly and candidate for the CI with significant improvement after implantation is EVA.