Aim. The aim of this work was to determine myocardial content of energy metabolites in rats in vivo with simultaneous evaluation of cardiac contractile function using noninvasive and invasive methods in doxorubicin cardiomyopathy model. Material and methods. Male Wistar rats weighing 250—300 g received subcutaneous injection of doxorubicin (DOX) at a dose of 2 mg/kg once a week for 4 weeks. Development of cardiomyopathy was observed during 8 weeks using echocardiograph Visual Sonic model Vevo 1100 with lineal probe 13—24 MHz. After 8 weeks, left ventricles of rats were catheterized with a PV-catheter FTH-1912B-8018 and used an ADV500 transducer («Transonic», Canada) for registration PV-loops in cardiac cycles and evaluation of cardiac contractility. The hearts were then frozen at temperature of liquid nitrogen using Wollenberger clamps for further determination of adenine nucleotides, phosphocreatine, creatine and lactate. Results and discussion. After 8 weeks, rats received Dox for 4 weeks developed chronic heart failure (CHF) with a reduced ejection fraction (EF) by 23—24% and a reduced fractional shortening (FS) by 13%. At the same time LV end diastolic volume and LV end diastolic dimension changed insignificantly. Myocardial adenine nucleotide pool (ΣAN), as well as contents of individual adenine nucleotides in the DOX group, did not differ significantly from those in the control group. Myocardial PCr/ATP ratio, which is one of the main indicators of cardiac energy supply, was significantly decreased by 37% due to a lower level of phosphocreatine (PCr). Myocardial content of total creatine (ΣCr=PCr+Cr) was reduced for the same reason. These alterations in cardiac energy metabolism were accompanied by a significant increase in myocardial lactate content. Conclusion. Systolic dysfunction is characterized by a violation of energy transfer in cardiomyocytes. This impairment of energy metabolism leads to myocardial distension deterioration, increasing LV end diastolic pressure and underlies in the contractile failure.