The number of cases of syphilis has increased in the United States and in many high-income nations. Otosyphilis is a less recognized complication of syphilis that can lead to irreversible sensorineural hearing loss. Different pathophysiological mechanisms have been proposed to explain hearing loss in otosyphilis. We review the literature on otosyphilis in adults and propose the need for future work in this field to identify better ways to diagnose, treat, and manage this disease. Patients with syphilis should be screened routinely for hearing loss, and all patients with new, sudden, or fluctuating sensorineural hearing loss should be evaluated for syphilis.