Forty-five patients suffering from Menière's disease were submitted to pressure chamber therapy: 20 with constant pressure (2.2 ATA, hyperbaric treatment) and 25 with continuous variations in pressure levels (from 1.7 to 2.2 ATA, alternobaric treatment). Oxygenation therapy consisted of one session per day lasting 90 minutes for 15 days during the acute attacks followed by five consecutive sessions per month during a follow-up of two years. For a control group we used 18 patients treated with 10 per cent intravenous glycerol during the acute episode and 8 mg tid of betahistine thereafter. We compared hearing loss, vertigo and tinnitus in the three groups 15 days after starting treatment and at the end of the follow-up, according to the criteria suggested by the 1995 Committee on Hearing and Equilibrium. We found no statistically significant differences in recovery from the cochlear-vestibular symptoms in the three groups at the end of the first 15 days of therapy, whereas hyperbaric and, in particular, alternobaric treatment permitted a significant control of the principal attacks of vertigo during the follow-up period. Hearing loss also showed a more significant and more persistent improvement in the patients treated with alternobaric oxygenation compared to the patients in the other two groups.