The effect of Epimedium-Propolis adjuvant (EPA) on the activities of natural killer cells, macrophages and serum concentrations of cGMP and cAMP in chickens and mice were evaluated in two experimental studies. Experiment I used 24 mice (4 wks old) randomly distributed into 4 groups (n=6) which were injected with EPA (Group 1), EPA and cyclophosphamide (Cy) (Group 2), cyclophosphamide only (Group 3), or saline (control, Group 4). This experimental protocol was repeated in 8 wk old mice. Splenic natural killer cells, peritoneal cavity macrophages and concentrations of cGMP and cAMP were collected and evaluated. Statistically significant results showed that splenic NK cell and macrophage activity of mice was greatest in Group 1 and decreased with the following sequence: Group 1 (treated with EPA only)> Group 4 (treated with physiological saline)> Group 2 (treated with EPA and cyclophosphamide)> Group 3 (treated with cyclophosphamide only). In Experiment II, 360 three-day old chicks were randomly divided into 3 groups (n=120) and injected with 0.4ml EPA (Group A), 0.2 ml EPA (Group B), or saline (control Group C). EPA enhanced the activity of NK cells in peripheral blood, the phagocytic activity of macrophages and concentrations of cAMP and cGMP in plasma of chickens. The Group A treatment had a greater effect than Group B (P<0.05). These results indicated that EPA could not only enhance the immunologic function of experimental animals in a dose dependent manner, but also resist the immunosuppressive effect caused by cyclophosphamide, especially in the young animal whose immune system is immature.