AIM: To investigate whether supplementation of male zooid of Antheraea pyi extracts (MZAPE) could enhance immune function of radiated tumor-bearing rats.METHODS: Eighty male Wistar rats were randomly divided into a control group, a simple radiation group, a MZAPE group, and a radiation plus MZAPE group. With the tumor model established by implanting Walker-256 ascites tumor cells, tumor weight and tumor control rate were calculated. The rats in the simple radiation and radiation plus MZAPE groups were underwent to radiation at 10 Gy within 2 d. In the MZAPE and radiation plus MZAPE groups, the MZAPE was gavaged at a dose of 16.53 mg/kg once a day for 7 d. T cell subsets in peripheral blood were determined by flow cytometry and the expression of IL-2, IFN-y, IL-4 and IL-10 in sera were determined by ELISA on the 8th d.RESULTS: The tumor weight of simple radiation group, MZAPE group and radiation plus MZAPE group was lower than that of control group (P < 0.01) and tumor control rates were 63.08% ± 6.43%, 69.86% ± 7.12% and 35.30% ± 7.67%, respectively. CD4+ T and CD8+ T cells in the peripheral blood of the simple radiation group were fewer than in control group. In the MZAPE and radiation plus MZAPE groups, the number of CD4+ T cells was higher while CD8+ T cells was lower than in the control and simple radiation groups. Expression of IL-2 and INF-γ in the radiation group was lower than in control group, and significantly enhanced during MZAPE therapy (P < 0.05). Expression of IL-4 and IL-10 in the radiation group had no significant changes compared with the control group, and decreased significantly after MZAPE treatment (P < 0.01).CONCLUSION: MZAPE administration may help improve the immune function of the radiated tumor-bearing rats and reverse the radiation-induced immune inhibition by promoting the proliferation of Ttielper cells and inducing the transdifferentiation from Th2 to Thl.