Increased susceptibility of high-productive dairy cows to infectious diseases is associated with metabolic stress which is developed on the background of a negative energy balance. The objective of our study was to determine the differences in metabolic parameters and blood leukocyte profiles in cows infected by bovine leukemia virus (BLV+) compared with non-infected cows (BLV−). The blood samples were collected from 150 cows of the Russian Black-and-White breed. The cows were housed at identical environmental conditions in one free-stall facility and were fed by the same diets. BLV status was determined by immune diffusion reaction and confirmed by enzyme immune assay. The blood serum concentrations of carbohydrate, protein and lipid metabolites were measures and the blood leukocyte profile was evaluated. The experimental data were analyzed using logistic regression analysis of binary data, (http://www.statistica-help.ru/node/28) (p₁) and linear model ANOVA (p₂), where the BLV status and correlation coefficient were taken as a random factor. Student t-test was perform to evaluate the statistical significance of differences between the groups. The serum concentrations of albumin, creatinine and ALT did not differ significantly between the groups, but the concentrations of the total protein (+6.89 g/L, p₁ ≤ 0.0001, p₂ ≤ 0.0141), globulin (+6.95 g/L, p₁ ≤ 0.0002, p₂ ≤ 0.0483), urea (+1.02 mM/L, p₁ ≤ 0.0020, p₂ ≤ 0.0006) and bilirubin (+2.01 μM/L, p₁ ≤ 0.0162, p₂ ≤ 0.0016) were significantly higher among BLV+ cows compared with non-infected cows, but the concentrations of glucose (−0.50 mM/L, p₁ ≤ 0,0007, p₂ ≤ 0.0940), triglycerides (−0.04 mM/L, p₁ ≤ 0,0384, p₂ ≤ 0.0065), alkaline phosphatase (−63.1 IE/L, p₁ ≤ 0,0384, p₂ ≤ 0.0065) and AST enzyme (−1.56 IE/l, p₂ ≤ 0.0713) were significantly decreased. According to clinical indicators of blood (WBC, RBC, HGB, HCT, MCV, MCH, MCHC, RDW) significant differences between the groups were not found. The data obtained confirm the assessment that bovine leukemia has effect on the biochemical parameters of carbohydrate, lipid, protein metabolism. The research was supported by the Russian Science Foundation, project number 14–16–00046.