An adoptive-transfer model using recombinase activation gene—deficient (RAG-1^−/−) mice was developed to evaluate CD4⁺ and CD8⁺ T cell responses to infection with Mycobacterium bovis bacillus Calmette-Guérin (BCG). After receiving immune, unfractionated T cells or T cell subsets isolated by fluorescence-activated cell sorter, the RAG-1^−/− mice were exposed to aerosol BCG, and the bacteria load in the infected organs was examined 4 weeks later. Adoptive immunity was expressed more effectively in the spleens than in the lungs. Although CD4⁺ or unfractionated T cells protected both lungs and spleens, CD8⁺ T cells conferred significant protection only in the spleens and not in the lungs. The results confirm that in addition to CD4⁺, CD8⁺ T cells also play a role in the prevention of bacterial dissemination. This transfer model may be useful for dissecting T cell responses to mycobacterial infection.