One of the diseases, presenting a major obstacle in increasing milk productivity is ketosis of dairy cows. The end of pregnancy and start of intensive lactation are the most important physiological period for cows. At that time metabolism falls under the greatest stress. Under such conditions the dominant role in maintaining the regulation, distribution and utilization of substrates belongs to the endocrine system. The present work presents the results of examination of insulin, cortisol, thyrotropic hormone, triiodothyronine, thyroxine, calcitonin and parathormone in plasma of healthy cows and those affected by ketosis. The study was conducted on cows in farms in six different regions of Ukraine. Blood samples were withdrawn in 104 cows (56 clinically healthy with negative urine tests for ketone bodies and 48 with positive tests and clinical signs of ketosis), in their from second to sixth lactation, with productivity rate from 5200 to 8300 L of milk per lactation. Conducted researches have shown that the endocrine system in ketotic highyielding cows is under considerable stress. Its compensatory mechanisms are directed to smooth the energetic deficit. The latter is manifested through an increase in cortisol level and decrease of insulin synthesis. The accumulation of ketone bodies in cow’s organism causes the dysfunction of endocrine glands, particularly of thyroid gland. We have revealed a significant decrease in triiodothyronine, thyroxine and calcitonin levels. Under these conditions the plasma levels of parathormone and thyrotropic hormone were significantly increased in most cows with ketosis. This fact gives an evidence of activation of compensatory mechanisms in case of hypothyroidism and significant loss of calcium by the organism.