Oxygen consumption rate of corneal epithelium must be known in order to estimate the effect of contact lenses conventional or hydrophilic on corneal metabolism. The in vivo measurements reported here were made with a polarograpbic oxygen sensor on a human eye. The oxygen consumption rate of the human corneal epithelium is estimated to be 2.8 microliters per cm2per hour at 33°C, in good agreement with previous data on rabbit corneal epithelium. The oxygen consumption rate is independent of oxygen tension from 620 mm Hg (80% O2) down to about 20 mm Hg.