Effect of a polyvalent inhibitor of proteinases from bovine lungs (industrial preparation -- ingitrile, commercial grade -- conntrical) on the state of kinin system was studied in blood serum of patients with extensive burns at shock periods and in acute burn toxemia. Decrease in content of kallikreinogene, which is typical for shock and acute, toxemia and which reflects the activation of kallikrein-kinin system, was less distinct in patients, treated with the inhibitor, than in patients, which were not treated with ingitrile. The early and rapid restoration in kininogene content and distinct inhibition of the total arginine-esterase activity were observed in blood serum after treatment with the inhibitor. The inhibitor did not affect the phase alterations in the carboxypeptidase N activity within the first 3 days after the burns; the distinct decrease in the enzymatic activity was confirmed within the first period of the burn shock. Within 24-48 hrs after the burns content of alpha1-antitrypsin was distinctly increased in patients treated with ingitrile as compared with the untreated group. The data obtained suggest that the polyvalent proteinase inhibitor causes a decrease in activity of the kallikreinkinin system in blood plasma and affects the enzymes participating indirectly in formation of kinins in burned patients. The data obtained are in agreement with the distinct clinical effect of the inhibitor. The doses of the inhibitor used in these studies did not cause normalizing effect on the activity of the kinin system components and on the clinical state of patients only in extremely severe cases of burn shock and in acute burn toxemia with letal outcome within the few days after the injury.