An experiment was conducted to investigate the effects of Yi-Fey Ruenn-Hou (YR) Tea, a combination of Chinese herbs, 10% licorice root, 10% American ginseng, 10% Radix Paeoniae alba and 70% green tea-soaked solution, on the cytokine modulation in Balb/C mice. Four groups of mice were administered either 1ml of drinking water (group A) or 2 mg/ml (group B), 8 mg/ml (group C), 40 mg/ml (group D) of a saturated solution of combined Chinese herbs daily for six months. The physiological and pathological characteristics of the mice were observed during the time, and the mice were weighed and at least two mice were sacrificed each month for pathological detection of the brain, heart, liver, spleen and kidney and cytokine analysis. The results revealed neither weight difference nor pathological change among the four groups, however, serum-cytokine assay indicated that the cytokine modulation effects are consistent, and the most obvious cytokine modulation effect was observed in group D, which was the highest dosage employed for treating the mice. TH2-pattern cytokines responded earlier and higher in group D than in groups B and C. Furthermore, the effect of YR Tea on cytokine modulation in vivo is predominantly TH2-pattern and is dependent on its dosage (P < 0.05).