It is suggested that the kininogenesis should be assessed from 3 forms of kallikrein which are detected on the basis of their kininogenase activity in whole blood plasma. Heating of blood plasma acidified to pH 3.0 for 15-20 min at 61 degrees C allows for the conditions under which the kallikrein inhibitors (alpha 1-antitrypsin, alpha 2-macroglobulin) are destroyed whereas kallikrein, prekallikrein, low- and high-molecular kininogens (HMK) are preserved, thus constituting a complex of proteins making the kininogenase reaction feasible. Addition of purified preparations of HMK to the neutralized samples of normal and sick individuals' plasma permitted the demonstration that as the kallikrein is raised, the kininogenesis gets actually activated, during which the blood manifests, in the presence of kallikrein hyperactivity, a sufficient amount of HMK. Provided the kallikrein content drops by 50%, the kininogenesis is reduced, which is accounted for by depletion of blood HMK. A 70%- and a greater decrease in the kallikrein content attests to the kininogenesis reduction because of the diminished levels of HMK, prekallikrein and kallikrein. The regularities described have been confirmed by the agreement between the blood plasma kallikrein level and the concentration of blood free kinins revealed during examination of 68 normal individuals and 231 patients suffering from different inflammatory-allergic diseases of the respiratory and hepatobiliary organs, and from diabetes mellitus.