Chemokines have been shown to play a critical role in the recruitment of leukocytes to transplanted organs. Animal models and clinical studies have demonstrated predictable temporal and spatial correlations between chemokine production and leukocyte infiltration into allografts. Antagonism of chemokines or chemokine receptors has been shown to delay leukocyte infiltration and prolong graft function, demonstrating an important role for chemokines in allograft rejection.