Dendritic cells (DCs) are the most potent inducers of immune reactions. Genetically modified DCs, which express tumor-associated antigens (TAA), can efficiently induce antitumor immunity and thus have a high potential as tools in cancer therapy. The gene delivery is most efficiently achieved by viral vectors. Here, we explored the capacity of influenza virus vectors to transduce TAA genes. These viruses abortively infect DCs without interfering with their antigen-presenting capacity. In contrast to other viruses used for DC transduction, influenza viruses can be efficiently controlled by antiviral pharmaceuticals, lack the ability to integrate into host chromosomes, and fail to establish persistent infections. Genes encoding a melanoma-derived TAA (MAGE-3), or the green fluorescence protein (GFP), were introduced into a high-expression avian influenza virus vector. Monocyte-derived mature DCs infected by these recombinants efficiently produced GFP or MAGE-3. More than 90% of the infected DCs can express a transduced gene. Importantly, these transduced DCs retained their characteristic phenotype and their potent allogeneic T cell stimulatory capacity, and were able to stimulate MAGE-3-specific CD8(+) cytotoxic T cells. Thus influenza virus vectors provide a highly efficient gene delivery system in order to transduce human DCs with TAA, which consequently stimulate TAA-specific T cells.