Twelve calves of the Red Spotted breed and its crossbreds born by first-calvers, kept in a large-capacity stable of a dairy farm, were subject to the study of the ontogenetic development of the values of the blood picture from birth up to the 10th day of age. The erythrocyte and leucocyte count, the packed cell volume and the relative and absolute number of neutrophils reached the significantly highest levels in calves before drinking the colostrum. The amount of haemoglobin, MCV and MCHC reached the highest values on the first day after birth. The values of the red blood picture decreased in the first week of life and reached the minimum on the tenth day. The leucocyte count decreased during the first to second day after birth, the decrease being due to a drop of the absolute number of neutrophils, and on the tenth day the leucocyte count returned to its initial value. Neutrophils prevailed in the peripheral blood of new-born calves whereas lymphocytes prevailed in the peripheral blood from the fourth day of life on. The amount of cosinophiles in the peripheral blood of the calves was about 0.5% up to the fourth day; on the seventh day it exceeded 1%. The relative number of monocytes was at its minimum level just after birth and showed a significant increase during the second to fourth day.