The effect of chronic coronary artery occlusion on the content of rat myocardial coenzymes Q (CoQ) and evaluation of the applicability of CoQ10 for limiting postinfarct remodeling have been investigated. Left ventricle myocardium hypertrophy was characterized by the decrease in CoQ9 (−45%, p < 0.0001), CoQ10 (−43%, p < 0.001), and α-tocopherol (−35%, p < 0.05). There were no differences between the parameters of postinfarction and sham-operated rats in plasma. Administration of CoQ10 (10 mg/kg) via a gastric probe for 3 weeks before and 3 weeks after occlusion maintained higher levels of CoQ in the postinfarction myocardium: the decrease in CoQ9 and CoQ10 was 25% (p < 0.05) and 23% (p < 0.05), respectively (versus sham-operated animals). Plasma concentrations of CoQ10 were more than 2 times higher (p < 0.05). In CoQ treated rats there was significant correlation between plasma levels of CoQ and the infarct size: r = −0.723 (p < 0.05) and r = −0.839 (p < 0.01) for CoQ9 and CoQ10. These animals were also characterized by earlier and more intensive scar tissue formation in the postinfarction myocardium and also by more pronounced cell regeneration processes. This resulted in the decrease in both the infarct size (16.2 ± 8.1 vs. 27.8 ± 12.1%) and also mass index of left ventricle (2.18 ± 0.24 vs. 2.38 ± 0.27 g/kg) versus untreated rats (p < 0.05). Thus, long-term treatment with ubiquinone increases plasma and myocardial CoQ content and this can improve the survival of myocardial cells during ischemia and limit postinfarct myocardial remodeling.