Hearing loss with an onset in the pre- or perilingual period is a common feature of many hearing loss syndromes, including Pendred syndrome (PS). Although first identified over 100 years ago, PS remains a diagnostic challenge for many clinicians. Its hallmark features include inner ear malformations, most commonly enlarged vestibular aqueducts (EVA), prelingual onset hearing loss and goiter, or enlargement of the thyroid gland. However, these features are not found in all patients with PS, and sometimes they are found in individuals whose clinical evaluations are not consistent with PS. A combination of thorough clinical evaluations and appropriate genetic testing can, however, usually provide an accurate diagnosis. This article presents information on PS, nonsyndromic hearing loss with EVA, the etiology and molecular aspects of these disorders, their epidemiology in various ethnic populations, and their distinguishing clinical and genetic features.