The rise and fall of the Opsonine rate in the blood during various general anesthesia was investigated. 1) The basal narcosis scarsely gave influences upon the Opsonin rate. 2) During the intravenous anesthesia using Penthothal sodium the Opsonin rate fell to the bottom at the second hour of anesthesia. 3) During the endotracheal anesthesia with cyclopropaine the Opsonine rate showed its least value also at the second hour. 4) During the endotracheal anesthesia with ether, the Opsonin rate showed a gradule and marked increase with the progress of anesthesia. 5) During the endotracheal anesthesia using cyclopropaine and nitrous oxide together the Opsonin rate decreased markedly and after hours it showed the least value, then began to increase from the third day after anesthesia and on the 7th and 14th days, it recovered to the rate before the anesthesia. 6) During the endotracheal anesthesia using the combination of cyclopropaine, nitrous oxide and ether, the Opsonin rate decreased markedly at the first hour of the anesthesia then considerably increased at the second hour but considerably decreased at the third hour. And it gradually increased from the third day after the anesthesia. 7) During the endotracheal anesthesia using nitrous oxide and ether, it decreased markedly at the first hour of anesthesia, while it showed gradual decrease from second hour to 7th day after anesthesia. 8) By oxygen inhalation the Opsonin rate showed a slight decrease temporally, but it recovered at the end of inhalation. 9) The influence of various general anesthesia upon the Opsonin rate in blood was independend of the blood coagulating time and the number of the platelets.