The hemodynamics and contractility function of the myocardium were studied in rats of 2 age groups with normal or increased arterial pressure under conditions of an acute experiment with the use of electromagnetic flowmetry. In the early hypertensive stage, the rise in arterial pressure is mainly caused by an increase in the cardiac output due to intensified work of the heart in normal peripheral resistance to the blood flow. With the gradual stabilization of the hypertension it is observed, on the whole, that the hyperkinetic type of circulation encountered in the early stage changes to eu- and hypokinetic types in the stage of stable hypertension when the high arterial pressure is maintained by the increased peripheral resistance to the blood flow while the contractility function of the myocardium is diminished.