The article discusses the results of the dy-namics of indicators of innate immunity of cattle throughout pregnancy. The research topic is relevant, since receiving healthy offspring is certainly associated with the natural resistance of the cow. The aim of the study is to study the non-specific immunity of cows in different months of pregnan-cy. The work was performed on the farm of JSC Krasnoselskoye PZ (Leningrad Oblast). During the experiment, 2 groups of cows of Holstein black-and-white breeds were formed: the experimental group – 10 preg-nant cows and the control group-10 not steel cows. Blood was taken once a month throughout pregnancy. Indicators of phago-cytosis, bactericidal and lysozyme activities were determined in the blood. During the study, the authors noted a decrease in lyso-zyme, bactericidal activity relative to the indicators of the control group, however, the difference did not reach significant differences. Also observed a sig-nificant inhibition of the functional state of the number of blood neutrophils: a decrease in phagocytic activity reliably observed from 5 months by 27.02%, from 7 month by 41.9% to 9 month, the index decreased by 50,66% as compared to control; at the phag-ocytic number of reliable decrease was ob-served at 4 months 11.3% at 6 months had decreased by 24.86%, and the 9 month preg-nancy reduction made up 28.81%, the phag-ocytic index, starting with the 5th month of pregnancy was significantly decreased by 32.05%, to 8 month decreased by 48.31% and for 9 months had decreased by 50% compared to control. Therefore, in the period of pregnancy in the organism of cows, the development of sec ondary immunodeficiency is noted, which is directly associated with fetal gestation. The data obtained can be useful in correction factors of natural resistance during pregnancy of cows.