Pulsatile flow characteristics in the ascending aorta were examined in 14 patients 12 months after aortic valve replacement with the glutaraldehyde-fixed porcine aortic heterograft. Analysis of the velocity signals permitted measurement of peak velocity, maximal acceleration, stroke volume, and ejection time in addition to the standard measurement of systolic aortic valvar gradient. Angiographic techniques permitted visualization of a pattern of blood flow in the ascending aorta. Valvar aortic gradients were minimal, and, when the phasic ascending aortic blood flow velocity parameters were compared to those in a group of eight patients with normal aortic valves, these characteristics of flow were nearly indistinguishable. This remarkable similarity to the flow characteristics of normal valves may be important to long-term performance of a prosthetic aortic valve. Our results suggest that the glutaraldehyde-fixed porcine heterograft warrants serious consideration when selecting a substitute aortic valve for man.