In vitro it was observed that NK 91 cxerted an excellent fungiostatic action against Candida albicans. So that, before clinical application, the author investigated about the fungiostatic action of NK 91 on experimental animals. The results were summarized as follows: 1) In the test of toxicity, mice which were given NK 91 subcutaneous injection over the certain quantity showed the symptoms of tachypnea and inactivity in the state of unrest and excitement and died finally. LD(50) in mice was 7.02 ± 0.38 mg/kg . 2) The hemolytic cation against the erythrocytes of rabbits occurred at the concentration of 5 γ / cc. It has been observed that the wandering velocity of neutrophils was moderate at the level of 1 γ / cc, slight accelerated at 10 γ / cc and slightly declined at 100 γ /cc. 3) The blood level of NK 91 in a non-oral administration maintained relatively high concentration in one to three hour, but declined rapidly with the lapse of time. 4) In respect of the protective test against the infection, it has been observed that the survival duration of experimental mice with Moniliasis were prolonged remarkably, compared with the control. 5) In therapeutic experiments, the author confirmed the remarkable decrease of Candida albicans in organs in the case treated with NK 91, compared with the control group in the case which was cultured from organs. Moreover, in the histologic investigations, the author observed the remarkable therapeutic effect in the treated group.