We investigated inner ear barotrauma in humans and in guinea pigs. The shapes of audiograms in patients with inner ear barotrauma were varied, such as high-tone hearing loss, profound loss, low-tone hearing loss, dip type, etc. In inner ear barotrauma in guinea pigs, damage to the organ of Corti was observed in various parts of the cochlear turns in varying severity. Some animals showed rupture of the round window membrane and/or reduction of endocochlear potential following the barotrauma but the rupture healed and EP recovered spontaneously within one week. We consider that irreversible hearing loss in patients with inner ear barotrauma depends on the extent of damage to the organ of Corti.