Binding of the P-, L-, and E-selectins to sialyl Lewisx (sLex) retards circulating leukocytes, thereby facilitating their attachment to the blood vessels of allografts. Whether the selectin inhibitor bimosiamose (BIMO; C46H54O16 · 0.25 H2O [867.4 molecular weight]) inhibits the rejection process of kidney allografts in a rat model was examined. Rat recipients acutely rejected kidney allografts at a mean survival time of 8.8 ± 0.75 d. An intravenous 7-d infusion by osmotic pump of 2.5, 5, 10, or 20 mg/kg BIMO extended kidney allograft survival to 11.5 ± 2.2 d (P < 0.03), 25.4 ± 11.4 d (P < 0.006), 37.4 ± 13.6 d (P < 0.001), and 39.8 ± 34.5 d (P < 0.01), respectively. Combination of BIMO with cyclosporine produced synergistic interactions, as documented by the combination index (CI) values of 0.34 to 0.43 (CI <1 is synergistic; CI = 1 is additive; and CI >1 is antagonistic). Similarly, BIMO interacted synergistically with sirolimus (CI = 0.64) and FTY720 (CI = 0.22). While the mechanism of immunosuppression was being analyzed, decreased infiltration of CD4+, CD8+, and macrophages on day 7 after grafting was observed. Multiple cytokines were also expressed, including IL-1α, IL-1β, IL-2, IL-4, IL-6, IL-10, IL-12, IL-18, TNF-α, and IFN-γ in kidney allografts on days 3, 5, and 7 after grafting, as measured by a ribonuclease protection assay. Furthermore, at similar time points, BIMO treatment reduced intragraft expression of P-selectin glycoprotein ligand-1, CX3CL1, CCL19, CCL20, and CCL2. Thus, BIMO blocks allograft rejection by reduction of intragraft expression of cytokines and chemokines.