An ultrasonic measuring system has been developed which is useful for fast and nondisturbing exploration of the flow field around models in wind tunnels, especially—according to its integrating method of operation—suitable for the measurement of vortices. It is based on the measurement of the flow-induced running time difference of short ultrasonic pulses, propagating along one or two measuring sound beams, requiring no critical adjustment and no special calibration. From the computer-aided evaluation of the measured data all essential parameters of the vortices under test (position in the flow, core diameter, maximum circumferential velocity, and circulation) can be determined accurately. The method has been successfully employed to steady and to unsteady vortices. In comparison to the conventional method of point by point measurement using directional pressure probes, the measuring times needed are, in general, reduced by about one order of magnitude. This property, besides leading to a corresponding reduction in costs, makes it especially valuable as a quasi real-time method for investigations concerning the influence of even small modifications of the model on the resulting flow field.