Objective To investigate the effect of Immutol on inducing the immune tolerance of cardiac grafts in rat models. Methods A rat model of heterotopic abdominal heart transplantation was established. The recipient rats were divided into 5 groups: blank control group (n=6); dimethyl sulfoxide (DMSO) group (n=6), in which DMSO was administered until the cardiac graft arrest; Immutol group (n=6), in which Immutol was administered until the cardiac graft arrest; ciclosporin (CsA) group (n=10), in which CsA was administered for 20 d; combined group (n=13), in which Immutol was given for 60 d combined with CsA for 20 d. The survival time and pathological changes of cardiac grafts in each group were observed. The contents of serum interleukin (IL)-10 and interferon (IFN)-γ were detected. The expression levels of indoleamine 2, 3-dioxygenase (IDO) and fibrinogen-like protein 2(Fgl2) messenger RNA(mRNA) in heart tissues of rats in each group were measured. Results In the combined group, the cardiac grafts survived for >180 d and immune tolerance was induced. The pathological score of cardiac grafts in the combined group was significantly lower than that in the CsA group at postoperative 39 d (P < 0.05). The levels of serum IL-10 and IFN-γ in the combined group were significantly higher than those in the CsA group at 9 d and 39 d after operation (both P < 0.05). The content of serum IL-10 and IFN-γ in the combined group were gradually increased over time. At postoperative 39 d, the expression levels of IDO and Fgl2 mRNA in the combined group were significantly higher than those in the CsA group (both P < 0.05). The expression level of IDO mRNA in the combined group tended to gradually elevate after operation. In the combined group, the expression level of Fgl2 mRNA at postoperative 180 d was significantly higher than those at 9 d and 39 d after operation (both P < 0.05). Conclusions Combined administration of Immutol and CsA can effectively inhibit the incidence of acute rejection, and maintain the long-term survival of the cardiac grafts and induce immune tolerance after drug withdrawal.