Dendritic cells are excellent targets for antigen-specific immune intervention. Here we attempted to introduce a CD8 T cell-dependent epitope into dendritic cells for presentation on major histocompatibility complex class I and induction of immunity. Murine bone-marrow-derived dendritic cells were subjected to electroporation with mRNA transcribed in vitro from a plasmid encoding lymphocytic choriomeningitis virus glycoprotein or enhanced green fluorescent protein under the control of a T7 promotor. The transfection efficiency of dendritic cells was 22 to 40%. Maturation was not inhibited by the electroporation. Dendritic cells electroporated with the appropriate antigen induced cell number-dependent in vitro proliferation in CD8 T cells expressing a transgenic receptor recognizing the 33 to 41 sequence of lymphocytic choriomeningitis virus glycoprotein in association with H-2Kb/Db, indicating correct synthesis, processing, and presentation of the epitope. Naive C57BL/6 mice vaccinated with electroporated dendritic cells and challenged with lymphocytic choriomeningitis virus were protected. Vaccination induced epitope-specific T cells as assessed by tetramer staining in blood and spleen. These results indicate that targeting dendritic cells with antigen-encoding mRNA can induce antigen-specific CD8 T cell responses as well as protective anti-viral immunity in vivo. Targeting dendritic cells with antigen-encoding mRNA may find wider application for immune intervention in disorders such as autoimmunity and cancer.