OBJECTIVE: To study the inhibitory effect of Danggui Buxue Tang (DBT), a compound traditional Chinese herbal medicine for supplementing blood, on tumor growth in tumor-bearing mice after inoculation of EL-4 cells, and its immune mechanism as well as its synergic effect in reducing toxicity of cytoxan (CTX). METHODS: Experiment was carried out in tumor-bearing mice after inoculation of EL-4 cells. The mice were randomly divided into four groups after 7 days of the inoculation: untreated group, DBT-treated group [24 g/(kg x d)], CTX-treated group [7.5 mg/(kg x d)] and DBT plus CTX-treated group, with another ten normal mice as control. Inhibitory rate of tumor growth, survival time, immune function and variability of blood cells were measured in the mice during the experiment. RESULTS: After treatment of relevant interventions for 15 days, the tumor in the DBT-treated group, CTX-treated group and DBT plus CTX-treated group grew slower than the untreated group (P<0.05). Murine survival time in the DBT-treated group, CTX-treated group and DBT plus CTX-treated group was lengthened as compared with that in the untreated group (P<0.05). Compared with the untreated group, all kinds of immune indexes in the DBT-treated group and DBT plus CTX-treated group were significantly improved (P<0.05), while the immune indexes in the CTX-treated group were decreased (P<0.05). Compared with the CTX-treated group, all kinds of immune indexes in the DBT plus CTX-treated group were significantly improved (P<0.05). CONCLUSIONS: DBT can enhance the immune function in tumor-bearing mice and the inhibitory effect of DBT on tumor growth is related to the enhanced immune response. DBT can also increase the therapeutic effects and reduce the side effects of CTX.