Hemolysis of red blood cells in dilute H2O2 was detd. according to the method of Gyorgy and Rose for 23 premature infants and 19 adults. All 19 adults showed hemolysis in H2O2 which was less than 10% of that in dist. water. For the premature infants, 24 of 32 observations showed hemolysis over 50%, and only 3 showed less than 10%. This susceptibility to H2O2 persisted as long as the infants were observed without tocopherol supplementation of their diets of cows'' milk mixtures. In each of nine trials in 8 infants, the in vitro hemolysis was reversed by feeding alpha-tocopherol. If it can be shown that the susceptibility of the red blood cells of premature infants to H2O2, and its reversal by alpha-tocopherol, have physiologic or clinical significance, then tocopherol should be added regularly to the diets of premature infants.