The purpose of this study is to evaluate the effectiveness of OTO-104 for the treatment of Meniere's disease.

Inclusion Criteria:

• Subject has a diagnosis of unilateral Meniere's disease by 1995 American Academy of Otolaryngology - Head and Neck Surgery (AAOHNS) criteria and reports active vertigo for the 2 months prior to the study lead-in period.
• Subject has experienced active vertigo during the lead-in period.
• Subject has documented asymmetric sensorineural hearing loss.
• Subject agrees to maintain their current treatments for Meniere's disease while on-study.
• Subjects currently on a low-salt diet and/or diuretic at the time of screening agree to continue this treatment throughout the study.

Exclusion Criteria:

• Subject is pregnant or lactating.
• Subject has a history of immunodeficiency disease.
• Subject has a history of previous endolymphatic sac surgery.
• Subject has a history of previous use of intratympanic (IT) gentamicin in the affected ear.
• Subject has a history of tympanostomy tubes with evidence of perforation or lack of closure.
• Subject has experienced an adverse reaction to IT injection of steroids.
• Subject has used an investigational drug or device in the 3 months prior to screening.
• Subject has previously been randomized to a trial of OTO-104.