Attempts have been made upon the temperature response of the rat induced by some central nervous system depressants as well as stimulants, so as to secure some hidden facets of Panax Ginseng acting upon central nervous system. Although considerable works have been done with regard to Panax Ginseng, it is quite apparent that neither definite implication in terms of its effective chemical constituents is with us nor its pharmacological activity thus far. The author could, however, arrive at some results through procedures preceded by intraperitoneal administration of various drugs in combination with Panax Ginseng in albino rats, that is: (1) Nembutal and chlorpromazine displayed a highly inhibitory effect upon temperature response in the presence of Panax Ginseng, while meprobamate, reserpine, phenacetin and aspirin exerted potentiation actions upon hypothermia. Phenobarbital, serotonin and histamine, on the contrary, did not appear to produce any effect of significance. (2) Nembutal with Panax Ginseng caused prolongation of hypnosis in rat, whereas sodium phenobarbital did not have any effect on it. (3) LD_-50 in each experimental group of administration of central nervous system stimulants such as strychnine, picrotoxin with Panax Ginseng, necessitated marked increase in the lethal doses. The observations from this study seemed to imply that the complicated mechanism of action of Panax Ginseng might be referred to both central nervous depressive action and influence to basal metabolic rate of mammalian.