This study tested the hypothesis that mean aortic velocity is relatively constant in children. Eighty-eight normal children (aged 1 month to 15 years) were studied prospectively. Ascending aortic flow velocities were obtained by pulse Doppler and mean aortic velocities calculated. Mean aortic flow velocity was relatively constant for all ages at 28.4 +/- 4.8 cm/s. As Doppler is easy to perform, mean aortic flow velocity may be an alternative approach to the assessment of cardiac output.