To determine the relations among color Doppler echocardiographic, pulsed Doppler echocardiographic and radionuclide angiographic fractions of left ventricular filling, 37 patients were studied using the three techniques. Favorable correlations of the filling fractions were found between color Doppler (flow area/left ventricular cavity area) and radionuclide angiography both during early diastole (r = 0.94) and atrial systole (r = 0.90). The above results were better than those obtained from pulsed Doppler (E area/Total, A area/Total) and radionuclide angiography: during early diastole (r = 0.78) and atrial systole (r = 0.76). Color Doppler can be used as a new method for assessing the pattern of left ventricular filling.