In vitro fluid dynamic characteristics of aortic valve prostheses were experimentally measured for physiological relevant pulsatile flows using hot-film velocimetry. The prostheses studied were (i) centrally occluding ball-in-cage and (ii) tilting disc valves. The valves sewn to a plexiglass ring were placed in a specially designed valve chamber. The valve chamber was mounted in a mock circulatory system in which glycerol solution was used as the blood analogue fluid. Physiological pulsatile flow experiments were conducted at a time-averaged flow rate of 86·7 cm3s−1, (mean Reynolds number of 1320 based on the cross-sectional averaged velocity with a tissue annulus, diameter, of 27 mm). With the aid of a three-sensor probe, the instantaneous values of the three velocity components (component along the axis, as well as radial and tangential velocity, components in a cross-section) were measured and used to compute the mean velocity profiles as well as turbulent normal stresses. The results showed that peak turbulent normal stresses were obtained at 108 ms after the opening of the valves with maximum magnitudes of 110 Pa, 45 mm downstream from the silastic ball valves, compared to about 35 Pa for the stellite ball valve. The largest turbulent normal stresses of about 150 Pa were obtained behind tilting disc valves in the minor flow region parallel to the tilt axis.