To analyze rejection and antiapoptotic effects of heme oxygenase-1 (HO-1) in kidney transplantations, to investigate the protective effects of endogenous HO-1 induced by hemin on acute rat kidney allograft rejection.We selected 27 Brown-Norway rats and 27 male Lewis rats as donors and recipients, respectively, randomly dividing them into three groups: kidney transplantation alone, hemin treatment group, and cyclosporine (CsA) group (n = 18). Six recipient rats were harvested on the first, fifth, or seventh days after operation among each group to examine histopathologic changes in renal tissuse, HO-1 protein expression, and acute rejection as well as to measure serum creatinine values.HO-1 expression in both the kidney transplantation model group and the hemin-induced groups were higher compared with the CsA group (P < .05–.01). The expression increased with the aggravation of rejection; the expression in the CsA group also increased after transplantation but was obviously lower than that of the hemin-induced group (P < .01). The rejection process was relatively mild as indenset by histopathologic examination. The serum creatinine levels among the hemin-induced group were lower compared to the kidney transplantation control group (P < .05), but higher compared to the CsA group (P < .05).HO-1 provided protection of allografts against rejection in rats, but such effects were poorer than those achieved using potent immunosuppressive agents like CsA.