This study shows that after viral or bacterial infection, antigen-specific CD8 T cells migrate to nonlymphoid tissues and persist as long-lived memory cells. These memory cells in nonlymphoid tissues exhibit effector levels of lytic activity, unlike their splenic counterparts. CD8 T cells differentiate into effector cells upon antigen encounter, which are crucial for immune responses against intracellular pathogens. After infection resolution, a stable memory population remains. While CD8 memory cells are found in secondary lymphoid organs, their migration patterns and relationships with memory populations in other tissues remain unclear. Previous studies suggest that memory T cells can migrate to peripheral tissues, indicating subsets with migratory preferences. Recent data also show that human memory T cells in blood can be divided into subsets based on chemokine receptor expression and effector function. In this study, C57Bl/6J mice infected with VSV showed that antigen-specific CD8 T cells were present in various tissues, including nonlymphoid ones. These cells expressed high levels of CD11a and were most prominent in nonlymphoid tissues. Similar results were observed with Listeria infection. Memory cells were detectable in all tissues at prolonged times after infection, with differences in response kinetics between tissues. Nonlymphoid tissues like lung, liver, and small intestine lamina propria contributed the majority of tetramer-positive cells. The number of cells in nonlymphoid tissues represented a substantial portion of the overall response. Functional differences were observed between lymphoid and nonlymphoid memory cells, with nonlymphoid cells showing higher lytic activity. These findings suggest that CD8 effector memory T cells generated via viral or bacterial infection are localized in nonlymphoid tissues. The study also highlights the existence of functionally distinct memory T cell subsets, with potential tissue-specific regulation and distinct homing molecules. The ability of memory cells in tertiary sites to exert immediate cytolytic activity provides a mechanism for improved survival of the organism via rapid containment of pathogens.This study shows that after viral or bacterial infection, antigen-specific CD8 T cells migrate to nonlymphoid tissues and persist as long-lived memory cells. These memory cells in nonlymphoid tissues exhibit effector levels of lytic activity, unlike their splenic counterparts. CD8 T cells differentiate into effector cells upon antigen encounter, which are crucial for immune responses against intracellular pathogens. After infection resolution, a stable memory population remains. While CD8 memory cells are found in secondary lymphoid organs, their migration patterns and relationships with memory populations in other tissues remain unclear. Previous studies suggest that memory T cells can migrate to peripheral tissues, indicating subsets with migratory preferences. Recent data also show that human memory T cells in blood can be divided into subsets based on chemokine receptor expression and effector function. In this study, C57Bl/6J mice infected with VSV showed that antigen-specific CD8 T cells were present in various tissues, including nonlymphoid ones. These cells expressed high levels of CD11a and were most prominent in nonlymphoid tissues. Similar results were observed with Listeria infection. Memory cells were detectable in all tissues at prolonged times after infection, with differences in response kinetics between tissues. Nonlymphoid tissues like lung, liver, and small intestine lamina propria contributed the majority of tetramer-positive cells. The number of cells in nonlymphoid tissues represented a substantial portion of the overall response. Functional differences were observed between lymphoid and nonlymphoid memory cells, with nonlymphoid cells showing higher lytic activity. These findings suggest that CD8 effector memory T cells generated via viral or bacterial infection are localized in nonlymphoid tissues. The study also highlights the existence of functionally distinct memory T cell subsets, with potential tissue-specific regulation and distinct homing molecules. The ability of memory cells in tertiary sites to exert immediate cytolytic activity provides a mechanism for improved survival of the organism via rapid containment of pathogens.