Abstract: Mice were given Ginseng by mouth at the dosage of 0.1g/kg/day for 3 weeks and then infected with trypnosoma. Ginseng administration was continued throughout the course of the infection. It was found that the disease process of trypnosomiasis was attenuated by this treatment. Trypnosomae appeared later in the blood and the life span of the treated mice was significantly prolonged as compared with that of the controls. However Ginseng in vitro at the concentration of 1×10^-5—1×10^-4 did not affect the activity of trypnosomae. Administration of Ginseng to rabbits by mouth at the dosage of 0.25g/kg/day for 3 weeks followed by an intraperitoneal injection of Ginseng of 0.2g/kg can prevent the development of fever produced by the intravenous injection of vaccine. However, this treatment did not influence the temperature of normal rabbits. The hypotension and intestinal spasm induced in dogs by intravenous injection of 0.003mg/kg of histamine phosphate were prevented by pretreatment with O.025g/kg of Ginseng intravenously.