The aim of the investigation was to estimate the serum concentrations of the major proteinase plasmin (PL) and some inhibitors of proteinases, such as alpha 2-macroglobulin (MG), alpha 1-antitrypsin (AT), and the specific complexes plasmin-macroglobulin (PL-MG) in order to study their role in the pathogenesis of dyscirculatory encephalopathy. All the above indices were examined in the sera of 35 patients with dyscirculatory encephalopathy (a study group) and 38 apparently healthy individuals (a control group). The authors determined the levels of PL, MG, and AT by the rocket immunoelectrophoresis technique using monospecific antisera against these proteins and those of specific PL-MG complexes by enzyme immunoassay. During the study, a significant increase in the level of PL and PL-MG complexes was revealed in the study group before and after treatment as compared with the controls. Prior to and following treatment, the serum concentrations of MG and AT in the study group did not differ from those in the control group. The findings may be used for further study of the pathogenesis of dyscirculatory encephalopathy.