OBJECTIVE To determine the long-term hearing outcome in patients with intractable vertigo caused by unilateral Ménière's disease who were treated with intratympanic injection of gentamicin. METHODS The study was a longitudinal analysis of hearing and control of vertigo in patients with unilateral Ménière's disease who received intratympanic gentamicin. METHODS Pure-tone thresholds and speech discrimination scores on audiometry were analyzed, along with the control of vertigo. Criteria described in 1995 by the American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) were used. Patients treated with intratympanic gentamicin had "definite" Ménière's disease and had intractable vertigo despite optimal medical therapy, no symptoms suggestive of Ménière's disease in the contralateral ear, and serviceable hearing in the contralateral ear. The study analyzed the outcomes of 34 patients for whom follow-up data were available for periods greater than 24 months after intratympanic gentamicin. RESULTS Complete control of vertigo (AAOHNS Class A) was obtained in 90% of the patients. Profound sensorineural hearing loss occurred as a result of gentamicin injection in 1 of the 34 patients (3%). When data from all patients were grouped together, hearing was improved in 5 (15%), unchanged in 23 (68%), and worse in 6 (17%) patients. This distribution of hearing outcome is similar to that in patients whose symptoms of Ménière's disease were managed with medical measures. Recurrent vertigo developed in 10 patients (29%) at an interval of 4 to 15 months after initially complete control. Treatment with additional intratympanic injection(s) of gentamicin did not result in a change in hearing. CONCLUSIONS The risk of hearing loss in patients treated with infrequent intratympanic injection(s) of gentamicin is low.