There are two distinct phenotypes of T cell cytokine responses that lead to different effector functions and different outcomes in disease processes. Although evidence suggests a possible role of the local microenvironment in the differentiation or localization of T cells with these phenotypes, there are no examples of divergent T cell cytokine phenotypes with the same Ag specificity concurrently existing in different tissue compartments. Using a CD8(+) T cell adoptive transfer model for graft-vs-host disease, we demonstrate that a potent type 2 cytokine response develops in the spleen while a potent type 1 cytokine response simultaneously develops in the testis. These experiments demonstrate for the first time that cytokine production can be oppositely polarized in different organs of the same individual. This may have important implications for organ-specific pathology in infection or autoimmunity: infections or autoimmune diseases that affect multiple organs may have heterogeneity in tissue cytokine responses that is not revealed in systemic lymphocyte cytokine responses. Therefore, attempts to modulate the immune response phenotype may ameliorate pathology in one organ while exacerbating pathology in another.