Previous studies have suggested that defective immune responses in early life may be related to the immaturity of neonatal antigen‐presenting cells. To test this hypothesis, we assessed the capacity of neonatal dendritic cells (DC) to prime and polarize in vitro human naive antigen‐specific T cells. We report that mature cord blood DC efficiently prime an oligoclonal population of antigen‐specific CD8 T cells, capable of cytolytic activity and IFN‐γ secretion. In contrast, cells primed by immature cord blood DC do not acquire cytolytic activity and secrete lower amounts of IFN‐γ. Upon priming by either immature or mature DC, neonatal T cells acquire markers of activation and differentiation towards effector‐memory cells. Our results demonstrate that, if appropriately activated, neonatal DC can prime efficient cytotoxic T lymphocyte (CTL) responses. Furthermore, these findings have important implications for the development of vaccine strategies in early life and for the reconstitution of a functional CTL repertoire after bone marrow transplantation.