AIM: To explore the effect of He Jie Tang (decoction for medication) on serum levels of T lymphocyte subsets, NK cell activity and cytokines in chronic hepatitis B patients.METHODS: Eighty-five patients with chronic hepatitis B were divided randomly into two groups. Fifty patients in group Ⅰ were treated with He Jie Tang (HJT) and 35 patients in group Ⅱ were treated with combined medication. The levels of T-lymphocyte subsets (CD3+,CD4+, CD8+), NK cell activity, cytokines (TNF-α, IL-8,sIL-2R) were observed before and after the treatment.Another 20 normal persons served as group 3.RESULTS: The level of CD4+ cells and NK cell activity were lower, whereas the level of CD8+ cells in patients was higher than that in normal persons (t = 2.685,3.172, and 2.754 respectively; P＜0.01). The levels of TNF-α, IL-8, and sIL-2R in chronic hepatitis B patients were higher than those in normal persons (t = 3.526,3.170, and 2.876 respectively; P＜0.01). After 6 months of treatment, ALT, AST, and TB levels in the two groups were obviously decreased (t = 3.421, 3.106, and 2.857respectively; P＜0.01). The level of CD4+ cells and NK cell activity were increased whereas the level of CD8+ cells decreased (t = 2.179, 2.423, and 2.677 respectively;P＜0.05) in group I. The levels of TNF-α, IL-8, and sIL-2R in group Ⅰ were decreased significantly after the treatment (t = 2.611, 2.275, and 2.480 respectively;P＜0.05) but had no significant difference in group Ⅱ after the treatment (t = 1.906, 1.833, and 2.029respectively; P＞0.05). The total effective rate had no significant difference between the two groups (x2 = 2.882,P＞0.05) but the markedly effective rate wass ignificantly different between the two groups (x2 = 5.340, P＜0.05).CONCLUSION: HJT is effective in treating chronic hepatitis B. HJT seems to exert its effect by improving the cellular immune function and decreasing inflammatory cytokines in chronic hepatitis B patients.The function of HJT in protecting liver function in the process of eliminating virus needs to be further studied.