Danggui Buxue Tang (DBT), a Chinese medicinal decoction that is used commonly for treating women's ailments, contains Radix Astragali and Radix Angelicae Sinensis. The ratio of Radix Astragali and Radix Angelicae Sinensis used in DBT should be 5: 1 as described in China in 1247 A.D. In order to verify the efficacy of this ancient formulation in stimulating the immune responses, DBT prepared from different drug ratios was applied onto cultured T-lymphocytes and macrophages. In cultured T-lymphocytes, DBT induced markedly cell proliferation, secretion of interleukin-2 and phosphorylation of extracellular signal-regulated kinase. In addition, the phagocytosis of cultured macrophages was increased by DBT treatment. The immunomodulatory effects of DBT were revealed to be the strongest in the extract derived from the drug ratio of 5: 1. The current results verified that the ancient formulation of DBT has been optimized in stimulating immune responses.