목적: Enlarged vestibular aqueduct syndrome (EVAS) is the most common congenital malformation of the inner ear and associated with sensorineural or mixed hearing loss. Bilateral deafness, progressive hearing loss or sudden hearing loss is a clinical features of patients with EVAS. We aimed to classify the clinical features of EVAS and evaluate their speech perception outcomes of Cochlear implants (CI) and compare to control group with normal structures 방법:A retrospective analysis was performed for 18 patients who were diagnosed of EVAS and underwent CI surgery at Asan Medical Center, within the 5 year period (Those with EVA +IP II were excluded). Control group consisted of 85 CI patients with normal inner ear structures. Korean Standard monosyllabic word recognition score (KS-WRS) were used to evaluate the outcome after CI surgery. 결과:The mean age of surgery for patients with EVAS was 3 years, and the age of surgery for the normal structure group was 2.6 years. Of 18 EVAS who underwent CI, 12 patients (66.6%) were deaf at birth, 6 patients (33.3%) had progressive hearing impairment. There was no statistically significant (p=0.199) difference in the mean Best score over five years between patients with EVAS (60%) and the control group (69%). The mean best score of patients deaf at birth (57%) was not significantly different compared to the mean best score of those who have progressive hearing impairment (64%). 결론:This study showed that patients with EVAS still benefit from CI, regardless of whether they were deaf at birth or had hearing impairment.