The absorption of oxygen and nitrogen from the middle ear cavity to the surrounding tissues has been studied quantitatively and 24-hour values have been calculated for subjects with normal ears and intact tympanic membranes. The studies have been made according to a method described earlier, where the central principle is a recording of the volume deviation of the tympanic membrane at changing pressure conditions in the middle ear caused by absorption of the respiratory gases. The investigation is limited to persons with a perfect tubal function. The normal absorption of N₂ and O₂/hour and/24 hours has been calculated as well as the corresponding pressure drop in the middle ear.