The research aimed at studying metabolic changes of erythrocytes in the calves surviving for a long period with total artificial heart of BRNO VII type. The authors studied partly the count of erythrocytes, the plasma levels of free hemoglobin and activity of glucose-6-phosphate-dehydrogenase enzyme. The changes found were compared with the levels measured in a group of 10 healthy calves. Constant decrease of erythrocyte count, slightly increased concentration of free hemoglobin in plasma and repeatedly decreased activity of the enzyme studied were found in the group of 4 experimental calves, from the 5th to 17th weeks of surviving. These changes can be explained by a long-term action of mechanical stress on the erythrocytes that pass through the pump of the total artificial heart. The cells damaged mechanically have the decreased energetic metabolism and, consequently, shortened viability. As young healthy animals with normal erythropoiesis which is stimulated by the application of drugs during the experiment are used, compensated anaemia develops, but it is not a limiting factor for the surviving of the calves with total artificial heart.