High doses of cyclosporin A (CsA) can not be used in the long term treatment of kidney allograft recipients primarily due to severe side effects. In the present study, we investigated the potential application of Cordyceps sinensis (CS) in the long term treatment of renal transplant patients. The renal function and survival rates of grafts and patients did not show significantly different between the control group and the treatment group. However, the incidences of complications were significantly lower in the treatment group compared with that in control group with the exception of those showing acute rejection. Furthermore, the dosage and the whole blood trough concentrations of CsA were significantly lower than control group. However, there was no significant difference in the serum level of IL-2 in the two groups. Interestingly, the serum level of IL-10 in the treatment group was significantly higher than that in control group. These data demonstrat that CS may be used in combination with a low dose of CsA in the long term treatment of kideny transplant patients.