Influences of psychological stress on the acquired immune system have not consequently been investigated. We found acute psychological stress to cause an increase in CD56+ and CCR5+ effector T cells in the peripheral blood of healthy human subjects (N=22), while skin-homing CLA+ T cells decreased. At the same time, we observed a stress-induced decrease in CD45RA+/CCR7+ naive and CD45RA-/CCR7+ central memory T cells, while CD45RA-/CCR7- effector memory and CD45RA+/CCR7- terminally differentiated T cells increased. This T cell redistribution translated into an increase in T cells expressing perforin/granzyme B and in Epstein-Barr virus-specific, cytomegalovirus-specific and influenza virus-specific CD8+ T cells. Thus, acute stress seems to promote the retention of less mature T cells within lymphoid tissue or skin while effector-type T cells are mobilized into the blood in order to be able to rapidly migrate into peripheral tissues.