Abstract: Method and apparatus for ultrasonic blood flow velocity measurement based upon the doppler principle (doppler measurement), combined with simultaneous echo amplitude imaging by employing ultrasonic pulses (echo imaging). The method is used for investigation of living biological structures, in particular during movement, for example a heart function. The main application will be in hospitals and the like. The doppler measurement and the echo imaging is effected sequentially with so short intervals that the echo imaging is updated with a sufficiently high rate for obtaining an acceptable picture quality, with the doppler measurement occupying a substantial portion of the time. The information is presented in real time on a display screen. A control unit synchronizes the doppler measurement and the echo imaging, and there is incorporated one or more transducers in the equipment.