Using the blind method, a group of 91 coronary heart disease patients were studied. A two-week course of obsidan therapy proved to be most effective in patients with two impaired vessels and also in patients with a simultaneous decrease in the heart rate and in the systolic blood pressure during the threshold exercise. A parallel increase in the stroke index during exercise and a decrease in the myocardial contractile function at rest (by echocardiographic findings) suggest that the decrease in the systolic arterial pressure is associated with a negative inotropic effect of the drug. A decrease in the heart rate and myocardial contractility was observed only in patients with initial tachycardia and the intact functional state of the cardiac muscle. The best antianginal response occurs when these effects are combined.