Haemodynamics studies of abdominal aortic aneurysm require data on the velocity in the normal section of the aorta. Centreline velocity waveforms were measured in abdominal aortic aneurysm patients proximal to the aneurysm using spectral Doppler ultrasound. Characteristic points were automatically found on 21 of the waveforms and their parameters were used to create an archetypal centreline velocity waveform. The maximum velocity was 45 +/- 13 cm s(-1), the minimum velocity was -15 +/- 11 cm s(-1) and the maximum diastolic velocity was 2.7 +/- 4.7 cm s(-1). The velocity wave is suitable for use as an input to in vitro or in silico investigations of abdominal aortic aneurysm haemodynamics.