The diagnostic and prognostic potentialities of the parameters of free-radical processes and high resolution ECG in coronary disease were evaluated. A relationship between oxidative resistance of the plasma (MDA concentration after 24-h copper-induced oxidation) and clinical characteristics of coronary disease (functional class of angina and high-resolution ECG parameters) was detected. Changes in ECG parameters directly correlated with MDA levels, the frequency of their registration reflects the severity of coronary disease. The absolute values of ECG, MDA, and their dynamics correlated with the severity of coronary disease and outcome of acute coronary syndrome, the prognosis was unfavorable for patients with MDA level >100 nmol/ml. The level of MDA increased by days 5-7 of observation in all patients with acute coronary syndrome, indicating exhaustion of the plasma antioxidant system during exacerbation of the coronary syndrome. Hence, evaluation of the plasma oxidative resistance and high resolution ECG can serve as a new diagnostic complex approach for detecting coronary patients with an unfavorable prognosis.