A study was made on the effects of Epimedium sagittatum polysaccharides on DNA synthesis of bone marrow cells of "yang deficiency" animal model caused by hydroxyurea with methods of cell culture in vitro and determination of 3H-TdR incorporating DNA of bone marrow cells. The results showed that after the treatment with 100 micrograms of Epimedium sagittatum polysaccharides, the cell multiplication rate was increased by 72% and DNA synthesis rate increased by 68%, in 1 x 10(6) cells.