Chemokines are a family of closely related chemotactic cytokines known to be potent attractors for various leukocyte subsets such as neutrophils, monocytes, or lymphocytes. We investigated the chemokine profiles in 26 patients who received unrelated allogeneic bone marrow transplantation (BMT) and evaluated the relationship of chemokines to transplant-related complications. We measured plasma levels of regulated upon activation normal T-cell expressed and secreted (RANTES), macrophage inflammatory protein-l a (MIP-$1{alpha}$), macrophage inflammatory protein-$1{eta}$ (MIP-$1{eta}$), and interleukin-8 (IL-8) at BMT day -7, day 0, and day 21. When compared with preBMT levels, the mean level of RANTES was significantly decreased at day 21, and the mean level of IL-8 was significantly elevated at day 21. Methotrexate given for graft-versus-host disease (GVHD) prophylaxis and postBMT infectious complication respectively may have contributed to these plasma chemokine level changes. The mean level of IL-8 was significantly higher in patients with infectious complications at day 21 (p=0.009). However, plasma chemokine levels were not associated with the development of acute GVHD and veno-occlusive disease (VOD). Since chemokine production acts in a local manner, plasma levels may not reflect the actual activity of chemokines in target tissue. Further experimental and clinical studies, including chemokine expression in target tissue, are warranted to define the roles of chemokines following allogeneic BMT.