Monitoring hematological parameters in dairy herds is central to assessing animal health and welfare. The main parameters of peripheral blood were studied in healthy cows of Holstein, black-and-white and red breeds at the age of 30-60 days of the 2nd lactation, raised in Western Siberia. Studies of erythrocyte, leukocyte and platelet parameters were carried out on a PCE 90Vet analyzer with smear microscopy for calculating the leukocyte formula. Standard methods of descriptive statistics or robust statistics were used. Intergroup comparisons were performed using one-way analysis of variance or the Krasker-Wallace test. Tukey or Dunn’s method was used for post hoc comparisons. When calculating reference intervals, we used the bootstrap method. The calculated average values of the erythrocyte, platelet and leukocyte components of the hemogram in most cases varied within physiological norms or were on the borderline. Animals of the Holstein breed had the most pronounced adaptive potential. Differences between breeds have been established in almost all studied indicators except the number of red blood cells, MCV, RDW, basophils, band neutrophils, and immunoreactivity index. Cows of the black-andwhite breed were characterized by the highest level of hematocrit (27.99 ± 0.31%), absolute number of eosinophils (Me = 0.207 ×109/l), platelets (279.5 ± 22.13 ×109/l), for red steppe hemoglobin (98.32±1.53 g/l), monocytes (0.29±0.01) and average platelet volume (6.42±0.08 fL). Certain reference intervals for the leukocyte profile of cows provide monitoring of health status, the ability to compare data with other breeds, and also allows for comparative monitoring between regions.