The hematological parameters were investigated in 40 Holstein-Friesian. The cows were in the second and third lactation. The blood samples were taken in four productive periods as follows: in the dry period (2-3 weeks before delivery), the postpartum period (0-2 weeks postpartum), in the middle of lactation (15-17 weeks postpartum) and late lactation (2-3 weeks before the start of drying). The findings of hematological values in Holstein-Friesian cows corresponded with reference values for a given type of animal. The periparturient period is characterized by a reduced number of red blood cells, decreased concentrations of hemoglobin, reducing the total number of leukocytes with the growth of neutrophils. The characteristic findings of the entire population of cows, regardless of the period of lactation is to draw the number of neutrophils and lymphocytes to the right and turn left into hemoglobin. This supports the exposure to stress in daily production. All parameters are arranged in the normal (Gaussian) distribution.