Abstract: OBJECTIVE: To study the effects of Schisandra Chinensis (SC) extract on prevention and treatment of immune dysfunction caused by radiation. METHODS：48 BALB/c mice were divided into 4 groups，SC treated group (SC 4 mg/g + 6 Gy for 396 s)，NS group (NS + 6 Gy for 396 s)，SC control group (SC 4 mg/g）and normal group (NS). WBC and lymphocyte subset(LYM) of peripheral blood were counted. Percentages of CD4+ and CD8+ T cells were measured by flow cytometry. Contents of IgG and C3 in mouse serum were analyzed by immunological turbidimetry. RESULTS：After irradiation，the number of WBC and LYM in peripheral blood of NS-treated mice was lower than that of normal control group [(3.73±1.05)×109 and (2.06±0.57)×109，respectively，P＜0.01]. Compared to NS group，the number of WBC and LYM of SC treated mice was higher [(6.43±0.76)×109 and (4.15±0.95)×109，respectively，P＜0.01]. There was no significant difference between SC group and NS group (P＞0.05). The absolute numbers of CD4+ and CD8+ T subsets and the levels of IgG and C3 were decreased after radiation (P＜0.01). Compared to NS group，the number of T lymphocyte subsets in SC-treated mice was higher than that of NS group (P＜0.01). CONCLUSION：SC could prevent the lymphocyte reduction and immune injury caused by radiation.

Key words: Schisandra Chinensis, radiation, immune function, lymphocyte, prevention