Oral administration of Shosaikoto (1.4g/kg) enhanced phagocytosis of casein-induced murine peritoneal macrophages and nitric oxide (NO) production of thioglycilate broth-induced murine peritoneal macrophages. To clarify the kind of compounds are responsible for this augmentation of macrophage function, ethanol-precipitation was carried out to produce two fractions: one of ethanol-precipitates (EP) and one ethanol-soluble (ES). The EP fraction consisted of polysaccharide and showed enhancement of phagocytosis and NO production comparable to Shosaikoto's. On the other hand, the ES fraction consisted of low molecular compounds and did not affect macrophage function. These results suggest a crude polysaccharide fraction plays an important role in Shosaikoto's macrophage activation.