On the basis of preliminary data, this larger bi-institutional continuation trial evaluating the efficacy and safety of early iron supplementation in preterm infants calls attention to the levels of vitamin E, a marker of antioxidant activity, during iron treatment. A total of 116 preterm infants were randomly assigned to receive at 2 or 4 weeks of age ( N = 62, N = 54, respectively) 5 mg/kg/d of nonionic iron polymaltose complex concomitantly with a daily dose of 25 IU vitamin E (as dl-alpha-tocopherol acetate) from 2 weeks of age. Vitamin E (alpha-tocopherol) levels, iron, ferritin, hemoglobin concentration, and reticulocyte count were recorded from 2 to 8 weeks of age. The morbidities of prematurity associated with free radicals formation were also documented. A gradual increase of alpha-tocopherol levels within physiological range (0.8 to 3.5 mg/dL) was found in the 2-week and 4-week groups during the study period with no difference among the groups ( P > 0.05 for all comparisons). At 8 weeks of age, iron and ferritin levels, hemoglobin concentration, and reticulocyte count were higher in the 2-week group. No correlation was observed between timing of both iron and vitamin E supplement and hemolysis or morbidities associated with prematurity. Thus, treatment of iron with vitamin E supplement at 2 weeks of age is, in our experience, an efficacious and safe treatment for improving anemia in preterm infants.