Twenty-nine patients with essential hypertension and thirty-seven without cardiac disease were examined electrocardiographically, polycardiographically and echocardiographically. Both the proportion of the left atrial systole in the hemodynamics and the size of the left atrium were significantly greater in hypertonics compared to healthy subjects. The parameters of left ventricular systolic function did not differ significantly, the parameters of diastolic function were significantly lower in hypertonics. Evaluation of the size and function of the left atrium supplements the clinical assessment of the functional state of the left ventricle at a period of its normal global systolic function but diminished diastolic function. The insufficient informative value of the electrocardiographic criteria of changes in the size of the left atrium (so-called Morris's index) and of the presence of the 4th heart sound in evaluating the severity of hypertension is pointed out. Since the presence of the 4th heart sound is clinically incorrectly interpreted, the need for consistency in its interpretation is emphasized.