The chemokine RANTES (regulated upon activation, normal T cell expressed and secreted) plays a significant role in the innate immunity, which is particularly important in the neonatal period. In this study, we aimed to investigate the ability of the neonate to increase plasma levels of RANTES in the first month of life, and the possible impact of breast feeding on this ability. The study population consisted of 125 healthy term neonates that were exclusively breast-fed (n = 62) or formula-fed (n = 63) for at least 1 month after birth. Plasma RANTES concentrations (ELISA) as well as circulating leukocytes and platelets were measured on days 1 and 30 of life. Median RANTES concentrations of the total group showed a significant increase between day 1 [1000 (448-2100) pg/mL] and day 30 [3688 (1488-5400) pg/mL, p < 0.0001], as did median total lymphocyte, T-cell, B-cell, NK-cell and eosinophil counts (all p values <0.0001). Monocyte and platelet counts did not change significantly over the neonatal period. Further analysis according to the mode of feeding showed that RANTES levels as well as leukocyte populations and platelet counts did not differ significantly between breast-fed and formula-fed neonates on either day 1 or 30. Healthy term neonates are capable of increasing plasma RANTES levels during the 1st month after birth independently of the mode of feeding.