Eight patients with large vestibular aqueduct (LVA) syndrome and acute sensorineural hearing loss that had not responded to intravenous treatment were treated with hyperbaric oxygen(HBO2) therapy. This was performed daily, with 15 treatments per course. Pure tone and speech audiometry were performed on all patients. The mean hearing recovery following HBO2 therapy (20.8 +/- 12.1 dB) was significantly higher than after intravenous treatment (2.3 +/- 7.2 dB) (P < 0.01), although treatment duration was not different between the two therapies. Of the eight patients, five showed complete or partial recovery after one course of HBO2 therapy, and their hearing levels have not since changed. The other three patients showed heating recovery during therapy, but treatment had to be repeated for two or more courses because of progressive or fluctuating hearing loss.We consider HBO2 therapy should be used to treat acute hearing deterioration associated with LVA syndrome if patients do not recover their hearing ability following conventional treatment