Objective: To determine the effect of a drug STEMB, which is a biostimulating tissue preparation based on chicken embryos, on the morpho-biochemical blood values of dry cows. Methods: The study was conducted on 60 Holstein cows, which were divided into three groups (group 1, group 2, and group 3), with 20 cows in each group. During the experiment, all animals in each group were subjected to the same condition of feeding and maintenance. The experimental animals were administered with the STEMB drug three times subcutaneously at an interval of 7 d within 30 d before calving. Group 1 were given 0.050 mL/kg body weight;group 2 were given 0.075 mL/kg body weight; group 3 were given 0.100 mL/kg body weight. Results: STEMB at 0.075 mL/kg body weight improved the blood cell composition, increasing the erythrocytes, hemoglobin, leukocytes, hemoglobin content, the total protein, albumins, alpha globulins, and gamma globulins. It reduced the beta-globulin index and provided a threshold level for the enzymes alanine aminotransferase, aspartate aminotransferase, and A, M, G immunoglobulins. Conclusions: Use of the STEMB drug with a dose of 0.075 mL/kg body weight given subcutaneously three times at an interval of 7 d within 30 d before delivery is optimal for the prevention of complications during calving and postpartum periods, thereby providing an improvement in the blood cell composition.