The aim of this study was to evaluate erythropoiesis in 198 healthy babies aged 0-6 months by determination of their blood count, serum transferrin receptor (STfR), and ferritin levels. Anemia and microcytosis were present in 9% and 13% of the sample, respectively. Microcytosis rate was as high as 45% in 6-month-old babies. In infants with normal blood counts, the values of sTfR/ferritin and sTfR-F index were increasing with the increase of sTfR and decrease of ferritin beginning from 2 months of age. In the 5- to 6-month-old group, sTfR concentrations, sTfR/ferritin ratio, and sTfR-F index were higher in infants with anemia and microcytosis. This research showed a high frequency of iron deficiency detected in otherwise healthy babies. Only problems with early weaning practices were found to be significantly more common in babies with iron deficiency.