The purpose of workis to discover productivity and to determine biochemical indicators changes in blood serum of different genotypes of cows in Eastern Ukraine. Investigations were made in "Plugatar" and "Kalinovskoe", Lugansk region. Three breeds of cows were used in scientific-domestic experience: controlconsisted of Red Steppe Breed, experimental1imported Holstein German selection animals, experimental2 -Ukrainian Black-and-White animals, brought from central areas of Ukraine. The conditions of maintenance were the same for experimental cows.Microclimatic conditions were characterized in warm period by high temperatures (38-40°C) especially at day time with stall-camp system of maintaining, free access to feeds.Macro and microclimate condition were estimated by physical capacities of air (temperature, relative humidity, solar flux level, atmosphere pressure) and chemical composition (carbon dioxide, ammonia, hydrogen sulfide content), powder pollution and microflora contamination.Health condition estimated by etiology, feed and water supplements. Humoral resistant factors were considered from interior indices of bloodblood serum bactericidal activity, lysozyme activity of blood serum, from cellular -neutrophil phagocytic activity. In blood serum of experimental cows were determined total protein content and its portions, carotene, alkalinity reserve, calcium, inorganic phosphorus, immunoglobulin level Ig M, Ig G, Ig A. It is established, that cows of Red Steppe Breed are well adapted to natural and climatic conditions of Eastern area of Ukraine. Animals of Ukrainian Black-and-White breed have well-adapted potential in nonspecific natural resistance and diary productivity during cold and transitional period (autumn, spring), at 10-12° C, relative humidity not higher 75 %, in summer period-respectively 20-24°C and humidity 75-80 %. Biochemical and clinical indicators strongly vary in non-adapted cattletotal protein content and gamma globulin, carotene and alkalinity reserve, calcium and phosphorus decrease in blood serum, that considered as stressful condition for unfavorable environmental high temperature. Animals can not reach their genetic potential, consequently, their productive indicators in milk yield 7,9 % less in comparison with Red Steppe Breed, 13.3% less than Ukrainian Black-and-White. To wide distribution of Holstein breed German selection in certain district of Ukraine should take priority of production and feed use, grown in climatic zone and to maintain animals in shady places during summer time (30-40°C