A dynamics of the changes of the red and while blood cell count during puerperium (1st-27th day post partum) was studied in 293 sows of the Czech White breed kept in typical large-scale production conditions. An average count of erythrocytes amounted to 5 513 000 +/- 385 514. In the course of puerperium their count slightly decreased in comparison with the value obtained on the first day p. p. (on the 10th day p. p. the decrease was even highly statistically significant - P less than 0.01). An average amount of hemoglobin was 12.48 +/- 1.22 g per 100 ml of blood; in the course of the nearly whole of puerperium it was slightly higher than on the first day p. p. (in the third week on the threshold of the statistical significance up to the statistical significance - P less than 0.10-0.05-0.01). The value of hematocrit did not fluctuate (average = 38.65 +/- 3.89%), sedimentation slowed down, especially from the end of the second week p. p. The protein of the blood plasma amounted, on an average, to 7.71 +/- 0.84 g per 100 ml; the protein content raised during puerperium in comparison to the 1st day .p. An average count of leukocytes during puerperium was in comparison to the 1st day p.p. An average count of leukocytes during puerperium 12 755 +/- 1529, and it slightly increased in relation to the 1st day p. p. The percentage of neutrophile granulocytes and lymphocytes did not change very much; it reached 46%: 45%. The character of the sow blood during puerperium fluctuated all the time between neutrophile and lymphocytic type with a slight tendency to the prevalence of neutrophile granulocytes. Nevertheless, the proportion of neutrophile granulocytes with rodlike nuclei decreased, and on the other hand, the proportion of neutrophile granulocytes with segmented nuclei increased (a nucleus shift to the right). Original values and ratio of the first day p. p. (T = 6.91%: Seg = 41.13%) changed in the average value of T = 1.93%: Seg = 43.96% during the whole puerperium.