Thirty-three patients with anemia and hypoproteinemia were anesthetized with cyclopropane and the changes in the peripheral blood corpuscles and the plasma protein were observed before and after anesthesia. 1) The number of the erythrocytes slightly increased already 20 minutes after starting anesthesia, while the leucocytes markedly increased. In the increase of the leucocytes, An increase of the neutrophils and an marked increase of the lymphocyte were observed. Hemoglobin as well as hematcrit increased, while the water content of blood and plasma decreased. 2) Total plasma protein increased and its fractioning revealed an increase of A/G ratio, slight increase of albumin, decrease of α-globulin as well as φ, slight increase of γ-grobulin and no change of β-globulin in percentage. From the quantitative point, there were observed an increase of Al. slight increase of β-Gl., decrease of φ, increase of γ-Gl. and no change of α-Gl.. 3) These changes in the peripheral blood corpuscles and the plasma protein are considered to be due to the temporary increase of adrenalin secretion caused by cyclopropane as stressor, though there may be some exemia (concentration of the blood) due to general anesthesia.