To explore the effect of CD40 blockade in suppressing acute rejection of renal graft in rats.With Wistar rats as the donor and male SD rats as the recipients, rat models of acute renal graft rejection was established. The rat models were divided into therapy group and control group, and in the former group, CD40 ligand (CD40L) monoclonal antibody was injected daily for 4 consecutive days starting on the next day following kidney transplantation. On day 5 after the transplantation, the renal graft was harvested for histological examination, and graft rejection was evaluated semiquantitatively.The mean semiquantitative score of the renal graft was 0.63∓0.52 in the therapy group, significantly lower than that of the control group (3.72∓1.48, P0.05).CD40L monoclonal antibody can inhibit acute renal graft in rats.