The diagnosis and treatment of fetal and neonatal diseases requires knowledge of gestational age-dependent reference ranges for most laboratory values. It was the aim of the present study to establish reference values for serum iron, transferrin, ferritin and ceruloplasmin concentrations in premature neonates, thereby paying attention to the possible changes with gestational age. Blood samples were taken from 100 premature neonates within the first hour of life. Total serum iron, transferrin, ferritin and ceruloplasmin concentrations were determined, transferrin saturation was calculated. Newborns who developed a presumed oxygen radical disease of prematurity were excluded from the study (n = 37), because previous investigations could demonstrate significantly lower serum transferrin and ceruloplasmin concentrations in prematures suffering one of these disorders. Related to gestational age, only serum transferrin concentration showed a statistically significant increase and correlation (r = 0.47; p < 0.0001) with rising age. Although statistically not significant, even serum ferritin concentration increased with rising age of the neonates. None of the investigated laboratory values correlated with birth weight. Only ferritin showed a slight, but statistically not significant increase with higher body mass. We conclude that gestational age-dependent changes of serum transferrin levels must be considered in the judgement of fetal and neonatal diseases, whereas total serum iron and ceruloplasmin concentrations remain rather constant at least during the last weeks of gestation.