The aim of this study was to evaluate the efficacy of pharmacological treatment (corticosteroids, vasodilators, vitamins, Betaserc) combined with hyperbaric oxygen therapy (HBO) in the sudden sensorineural hearing loss (SSNHL). We reviewed 52 patients with SSNHL treated pharmacologically and with HBO (group A) between 1997 and 2000. All patients in this group received once daily, five days a week, 100% oxygen in a multiplace chamber under pressure of 2.5 ATA for 60 minutes (plus two 5 minutes air breaks). The other group (group B) consisted of 81 patients treated only pharmacologically between 1980 and 1997. Both groups were similar regarding age, season of the year in which deafness occurred, presence of vestibular symptoms and tinnitus, therapeutic delay from initial symptoms to start of treatment, and initial hearing loss, however there were significant differences in gender and shape of hearing loss. The improvement after treatment was measured by tonal audiometry. The retrospective analysis of audiometries performed in all patients was conducted. The improvement of hearing loss was statistically significantly better for group A (vasodilators, high-dose of corticosteroids, vitamins, Betaserc, HBO) than group B (vasodilators, lower-dose of corticosteroids, vitamins) in any single frequency (500-1000-2000-3000-4000-6000-8000 Hz) and in 4 ranges of frequencies (PTA, HTA, PMTA, OAA) both for relative and absolute values. We concluded that the combined therapy of high-dose corticosteroids and HBO improved the clinical results of treatment in the SSNHL, and therefore should be performed in such cases. We also observed that therapeutic delay and flat hearing loss are predictors of poor clinical outcome.