Doppler indexes have been used successfully to determine the severity of aortic regurgitation (AR) in adults but have not been evaluated in children. To determine the accuracy of pulsed, color, and continuous-wave (CW) Doppler echocardiographic indexes in assessing the degree of AR in children, the correlation between the non-invasive measurements and angiographic grading of the regurgitant flow (1+ to 4+) was examined in 14 children (mean age 11 +/- 3 years) with chronic AR. Forward and reverse flows in the aortic arch were evaluated from the suprasternal notch using pulsed Doppler. Aortic time-velocity integrals (TVI) were measured during systole (forward flow) and diastole (reverse flow), and the ratio of reverse to forward TVI (%) was calculated. Doppler color flow mapping was used to detect and assess the severity of AR (which appears as mosaic turbulent signals extending in the left ventricular outflow tract during diastole) by using four color Doppler grades of severity. The envelope of the flow velocity pattern in diastole was recorded from the CW Doppler signal of AR with the transducer in the lower sternal border to determine the peak flow velocity and deceleration slope (alpha) indexes. The ratio of reverse to forward aortic TVI and color flow mapping grading showed strong correlation with angiographic grade (r=0.92 and r=0.86, respectively) but AR slope (alpha) and peak flow velocity did not correlate well with the angiographic grade (r=-0.039 and r=0.74, respectively). We concluded that the severity of AR in children as determined by angiographic grading can be estimated with reasonable accuracy by noninvasive technique based on color and pulsed wave Doppler. Use of these indexes may obviate the need for angiography to detect the severity of AR in children.