The aim of the study was to assess the transcriptional activity of the metalloproteinase 9 (MMP-9) and tissue metalloproteinase 1 (TIMP-1) genes in peripheral blood mononuclear cells (PBMCs) in a study group of patients with heart failure due to myocardial ischemia and in the control group, as well as to evaluate the transcriptional activity of the examined genes, taking into account the number of affected coronary arteries and severity of heart failure (LVEF%). The gene discussed is MMP9; the disease is heart failure.