The effect of a prophylactic treatment with tocopherol, early iron substitution and administration of polyunsaturated fatty acids in different quantities on the plasma concentration of vitamin E, hemolysis in the peroxide test and hematological parameters during the first two months of life was determined in 23 premature infants with birth weights of less than 1800 gms. In no patient in any of the different treatment groups a tocopherol deficiency (plasma concentration less than 0.50 mg/100ml) was observed and accordingly no hemolytic anemia attributable to E hypovitaminosis was found. The mean concentration of tocopherol at birth (0.51 mg/100 ml) was already above the critical limit, and no single value was found below the latter after the 10th day of life. For that reason, the amount of vitamin E included in formulas generally used in this country and its intestinal absorption have to be considered as adequate even for small premature children. The different treatments of the test groups had no significant influence on the clinical state or the hematological findings. The infants with vitamin E substitution and those without had similar hemoglobin levels. Almost all children had a distinct reticulocytosis and thrombocytosis during the second month of their life. This seems to occur naturally. The peroxide test proved to be no reliable indicator of a tocopherol deficiency in the individual case. It is not yet clear which additional factors cause vitamin E deficiency, infrequently seen in small premature infants.