The purpose of this study was to determine the hematological effects of daily iron supplementation for eight months towards improving iron status of healthy infants who are exclusively breast fed until four months of age. The infants in the study group who had received 1 mg/kg/day iron supplementation regularly from four months (n=90) were compared with infants who had not as the control group (n=27). Iron deficiency and iron deficiency anemia rates in the study and control groups were 20% and 2% versus 26% and 30%, respectively. Even though iron deficiency or iron deficiency anemia was also diagnosed in infants who had received iron supplementation, they were less likely to develop iron deficiency anemia than controls (p=0.000). We concluded that it might be better to continue iron supplementation up to one year of age. Anahtar Kelimeler : demir proflaksisi, süt çocukluğu, demir eksikliği ve demir eksikliği anemisi, iron supplementation, infant, iron deficiency, iron deficiency anemia