The study of the myocardium state of cattle with the usage of electrocardiography makes it possible to diagnose many types of cardiac pathologies. This helps to select the optimal treatment and prevent loss of animal productivity. The purpose of the research is to study the features of the electrocardiogram (ECG) of cows with myocardial dystrophy during the postpartum period. The studies were conducted in “Gridino” - agricultural production cooperative in Kostroma region, on highly productive clinically healthy (n=5) cows and cows with the clinical symptoms of the myocardiodystrophy (n=15), both groups were of Kostroma breed, 20 days after calving (3-4 lactation). ECG traces were recorded in six cardiographic leads: three standard and three augmented leads (aVR, aVL, aVF) via veterinary electrocardiograph “Poly-Spectrum-8/B” (Russia). Animals were in a freestanding position, the leads were traced using clamp electrodes, which were fixed to the skin on the left and right side of the chest and pelvic limbs according to the standard technique. For the ECG analysis, the amplitude (mV) and the directions of the P, Q, R, S, T waves were considered as well as the duration of the P wave and the intervals P-Q, R-R, Q-T (ms). It was found that for clinically healthy cows the length of the P wave was 71,8±1,9 ms, and for others with the symptoms of the myocardiodystrophy it was 9,5% more. The P-R interval of clinically healthy animals lasted 181,2±8,0 ms, while the one of sick cows was 12,6% less. The height of the clinically healthy cows P wave in leads I and II was 0,15±0,02 and 0,19±0,01 mV, respectively, while the voltage of the P wave of sick cows was 40% lower in lead I (P <0,05), and in II – by 21%. The clinically healthy cows had the Q wave voltage in the range from -0.08±0,01 to -0,12±0,01 mV, and the R wave voltage – from 0,24 ± 0,02 to 0,53 ± 0,04 mV. The cows with symptoms of myocardiodystrophy showed similar tendency, but in lead II the R wave was 47.2% less (P <0.01). Among the sick cows, the S wave was absent in lead I in 80.0% of cases, in lead II – absent at all, and in lead III it was not recorded in 60.0% of animals, the rest 40% had the wave -0,28±0,18 mV, which was 2 times deeper than one of clinically healthy animals. The T wave of all cows with symptoms of myocardial dystrophy was low and variable in the direction in lead I, and in lead II in 80% of cases it was 3 times less (P <0.05) than one of clinically healthy animals. In lead III, it was observed negative in 20.0% of cows, but its voltage was within the normal range, while in 60.0% of animals it was positive (0.10 ± 0.02 mV), and in 20.0 % - not registered. Thus, according to the results of electrocardiography, clinically healthy cows in the postpartum period showed signs of left atrial hypertrophy. The cows with symptoms of myocardial dystrophy detected violation of the myocardial contractility ad function of conductivity, a decrease in the voltage of the P, R, T waves and a reduction of the time of impulse conducting through the atria.