Abstract: A dual transducer probe for measuring blood flow by Doppler effect measurement in which quantitative flow data can be compiled and flow constriction points as small as 10% and less can be pinpointed with relative ease. The probe is formed with two transducers, oriented at about 45.degree. from a bottom contacting surface of the probe so that transmission signals diverge at an angle of about 90.degree.. A first transducer directs pulsed sound waves into the direction of blood flow and a second transducer directs pulsed sound waves with the direction of blood flow. The transducers act as receivers for the respective pulses. Fluid velocity can be calculated due to the Doppler effect. By analyzing the signal frequency shifts from the two transistors the blood flow at a very minute region between the transducers, can be determined. Constrictions, corresponding to changes in flow can be pinpointed by moving the probe along the blood vessel.