1. The oxygen consumption VO2 of the whole cochlea VO2=AVDO2× flow/100 g wet weight is 0.6–0.8 ml O2/min×100 g wet weight. 2. Two ways in oxygen transport to the inner ear exist: a) by blood circulation, b) by diffusion from the middle ear cavity through fenestre membranes to the inner ear fluids. 3. Calculations of the oxygen transport through the fenestre membranes indicate, that a maximum of 10–15% of the oxygen consumption of the first turn-representing the high tones area is based by diffusion at high levels of PO2 in the middle ear cavity (400 mm Hg). 4. This oxygen transport by diffusion alone is not sufficient to prevent the disappearance of DC-potential induced by systemic anoxia during N2-breathing.