A plasmid DNA and gold nanorods were directly injected to tumor in mice, and the tumor was heated to 39-42 degrees C through the photothermal effect of the gold nanorods. The heat treatment enhanced transgene expression from the plasmid DNA in the tumor and induced heat shock protein HSP70, related to several immune responses. This transfection technique combined with heat treatment will be applicable to DNA vaccination and gene therapy for immunological diseases.