The focus of the article is rather situated on current faults and recommendations for transfusion of red blood assessment, clinical evaluation of changes in hematocrit. The main task of therapy for acute massive blood loss is not urgent thoughtless transfusion of red blood cells for the fast recovery of the hemoglobin and hematocrit levels. The oxygen-carrying capacity of blood does not directly reflect the delivery of oxygen to tissues. The severity of the patient's condition depends of individual ability of the organism to resist hypoxia, mechanisms resulting in physiological compensation for the anemia caused by blood loss. The main tasks of therapy are timely maintaining appropriate and effective compensatory-adaptive reactions of an organism, providing of the sanogenetic processes. Quickly and comfortable algorithm assessment changes in hematocrit was presented for used in practice. Objective analysis hematocrit and hemoglobin levels should be carried out only in combination with data on blood pressure, pulse rate, respiratory rate, urine output and shock index.