Dendritic cells (DCs) behave as antigenic or tolerogenic immune response inducers depending on the nature of their precursors, their differentiation pathway and their environment. As professional antigen presenting cells (APCs) it has been tempting to genetically modify them in order to improve their capacity to mount appropriate protective immune responses. Gene transfer may also be helpful to investigate fundamental issues about the DC biology. Of note, almost all strategies to deliver genes or interfering RNA into DCs have been used with different success rates. These methods are non-exhaustively presented and discussed here. We focused our attention on promising in vitro as well as in vivo lentiviral- mediated gene delivery solutions into murine or human DCs.