The noninvasive determination of severity of mitral regurgitation (MR) is often of major clinical importance. We performed simultaneous Doppler echocardiography and left ventricular angiography in 24 patients with MR, comparing a new Doppler echocardiographic technique with angiographic criteria for severity of MR. Angiographic severity was measured on a 1+ to 4+ scale, determined by the degree of opacification of the left atrium during left ventricular systole. The echocardiographic examination consisted of color flow imaging and continuous-wave Doppler echocardiography across the mitral valve. The product of the mitral regurgitant color flow jet area and the mitral regurgitant time-velocity integral was obtained, yielding a Doppler-derived regurgitant volume across the mitral valve. Good correlations were demonstrated between the severity of angiographic MR and the Doppler-derived regurgitant volume (r = 0.831; p < 0.005) and between the angiographic severity of MR and the Doppler-determined mitral regurgitant jet diameter (r = 0.833; p < 0.005). We conclude that a new Doppler echocardiographic method for quantitating the severity of MR correlates well with qualitative angiographic grading. Further study is needed to compare this technique with other quantitative Doppler indexes of severity of MR.