Measurement by Doppler-echocardiography of blood flow rates has the advantage over techniques for the measurement of cardiac output of determining the latter for each valve orifice, and of opening up an approach to the quantification of aortic and mitral regurgitation. This prospective study involving 103 subjects free of any valve leak showed the absence of an significant difference between aortic, pulmonary and mitral ring flow rates in a given individual. Correlations between results obtained at the three measurement sites were: r = 0.92 between aorta and pulmonary artery, r = 0.90 between aorta and mitral ring and r = 0.90 between pulmonary artery and mitral ring. These results support the validation of this technique and would justify its use in the evaluation, quantification and monitoring of mitral and aortic valve leaks.