The blood flow rate in the supra-hepatic veins has been measured by Doppler ultrasound in 11 subjects suffering from more or less advanced constrictive pericarditis; the results were compared to those obtained with normal subjects. In all the pathological cases, the flow rate curve shows the following modifications: a slight decrease in the X peak, which is related to the blood "demand" caused by the decrease in the ventricular volume during the ejection, and a correlative increase in the Y peak, contemporaneous of the ventricular filling up. In the patients in which the pericarditis has not reached a marked stage of constriction, the intra-thoracic ventilatory pressure variations still exert a certain influence on the supra-hepatic blood flow rate; on the other hand, this influence is suppressed when the constriction is complete. These phenomena are parallel to the pressure modifications observed by catheterism and to those of the mitral and tricuspid transvalvular flow. The advantage of measuring the blood flow rate in the supra-hepatic veins lies in the fact that the access, for ultrasound analysis, to these vessels is quicker and more constant than to the heart valves. This method seems therefore to be an interesting one to assess the stage of development of the constricting pericarditis.