The cardioprotective effect of ubiquinol on the model of myocardium reperfusion injury in rats was investigated. The study was carried out using mature males of outbred rats. Myocardial ischemia-reperfusion injury was performed after 30-minute ligation of the left coronary artery followed by reperfusion. The main criteria for assessing the development of pathology included the results of electrocardiography, biochemical analysis of blood plasma, histological and histochemical study of the myocardium. Development of the reperfusion damage of the myocardium caused specific changes in non-treated animals. The best therapeutic effect on biochemical indices was provided by a drug with the known cardioprotective activity - Mexidolâ and the tested object ubiquinol at doses of 2-6 mg/kg. Evaluation of the results of electrocardiography allowed to confirm the development of ischemic myocardial damage in all groups. The results of histochemical and histological examination of the myocardium suggest a high cardioprotective activity of ubiquinol at a dose of 3 mg/kg and a potential cardioprotective effect of ubiquinol in doses closest to the therapeutic doses of 2 and 6 mg/kg. Ubiquinol is a dose 9 mg/kg showed signs of prooxidant activity, manifested in the form of aggravation of reperfusion injury of the myocardium. The most effective in the conditions of experimental pathology is 1% solution of ubiquinol, at a dose of 3 mg/kg, whose cardioprotective effect is comparable or higher than that for the reference drug Mexidolâ at the therapeutic dose. In doses that are greater than therapeutic ubiquinol is able to act as a pro-oxidant.