Abstract: Investigations were carried out on the influence of polysaccharides of ginseng (PSG)on immune function. PSG was found to be able to markedly stimulate phagocytosis of the reticuloendothelial system and the prodaction of antibody. In addition, PSG causedan increase of serum complement, content in quinea pigs, and raised serum IgG level in mice. Besides, an increased B-lymphatic to T-lymphatic cell ratio was observed after PSG administration.The toxicity of PSG in mice was found to be very low. When PSG was administered orally to mice at a dose of 30 g/kg, neither death nor marked toxic effect, other than sedative appearance, was observed.