Twenty-nine patients with acute atherothrombotic ischemic stroke and 36 patients with acute Q-wave myocardial infarction have been studied. Each group has been stratified into 2 subgroups: patients of subgroups A received an ACE inhibitor perindopril in the complex therapy from the 1st day of disease. Patients of subgroups B were not assigned to this drug. Along with routine tests, the level of tumor necrosis factor-alpha and matrix metalloproteinase-9 (MMP-9) measured with ELISA using test-systems (BCM Diagnostics, USA) and reagents (R&D, England) have been determined. The administration of perindopril did not cause side-effects, including arterial hypotonia after the first dosage, in patients in the acute period of atherothrombotic ischemic stroke and myocardial infarction. Perindopril may decrease the activity of MMP-9 in these patients and produces an anticytokine effect. Some similar mechanisms of ischemic lesions of the heart and the brain and a commonness of biochemical "response" to the same medical intervention (the administration of an ACE inhibitor perindopril) in patients of both groups were found. The results support the pathogenetic validity of perindopril therapy in the secondary prevention of ischemic stroke and myocardial infarction.