The author studied the action of the polysaccharides extracted from the bone marrow on the blood pressures as well as the side-effects when administered intravenously in human body; and obtained the following results: 1) These polysaccharides exert no influence on the arterial blood pressure of normal dogs, nor do they show tachyphylaxis. 2) These substances exert no influence whatsoever on the venous blood pressure in normal dogs. 3) These substances likewise in no way affect the blood pressures in human beings. 4) As regards the side-effects when administered intravenously in human body, in the majority of cases there appear a transitory flushing of the face, clizzness, and tachycardia, and occasionally a slight sweating, thirst. sleepiness, rash and fever, but they are in no way to be of a serious nature, as these side effects will gradually disappear with repeated uses of them. 5) It seems that the general conditions of an individual have nothing to do with the occurrence and severity of these side effects but have a great deal to do with individual susceptibility.