Using the continuous-wave Doppler technique of transcutaneous aortovelography (TAV), aortic blood velocity was measured in 66 normal individuals at rest and during maximum voluntary supine exercise. Stroke distance (the systolic velocity integral: a measure of stroke volume), minute distance (a measure of cardiac output=stroke distance times heart rate) and peak velocity increased significantly with exercise, but flow time shortened slightly. Stroke distance was found to rise to a plateau of 24% above the resting value at low work rates during exercise. This relatively undemanding noninvasive technique for measuring haemodynamic response to physiological stress may prove valuable in the assessment of left ventricular function. Our results in normals are consistent with findings by other techniques and provide a basis for clinical comparisons.