In this study, we examined the relationship between levels of lactoferrin (LF) and IL-17 in human serum and breast milk and the development of allergy in children. LF and IL-17 levels were determined by ELISA in healthy (n=19) and allergic mothers (n=21) on the 5th day after delivery. Two years later, information on breastfeeding and allergic outcomes was collected by questionnaires from parents of both groups and district child care nurses. Significantly higher concentrations of LF were found in the breast milk of allergic mothers compared to the healthy controls. At 2 years of age, only those three infants became allergic from the atopic group in whose starting breast milk samples a very high LF level (306 μg mg–1 protein) or simultaneously elevated concentrations of LF and IL-17 were measured. These findings indicate that the very early measurement of LF and IL-17 levels in the breast milk of allergic mothers may help to predict the allergy development in their infants.