1) The basal narcosis caused no change of the serum sterilizing power. 2) In the intravenous anesthesia using penthothal sodium the sterilizing power showed a temporal decline but after the end of anesthesia it slightly increased. 3) In the endotracheal anesthsia with cyclopropaine, the sterilizing power always showed a marked decline. 4) In the endotracheal anesthsia with ether, the sterilizing power showed a temporal decline during and after anesthesia. 5) In the endotracheal anesthesia using cyclopropaine and nitrous oxide or with additional ether together, the serum sterilizing power varied as well as in that using cyclopropaine only, but did not decline so distinctly. 6) The variation of sterilizing power in the endotracheal anesthesia using nitrous oxide and ether together showed a very gradual decline and then also gradually recovered. 7) The variation of the sterilizing power caused by oxygen inhalation showed clear increment with the beginn of inhalation namely the oxygen inhalation is very important for protecting sterilizng power of serum from inhibition of it. 8) The influence of various general anesthesia upon the serum sterilizing power was independent from tne Opsonin rate in the blood coagulating time and the number of platelets.