Abstract: A flowmeter for measuring blood flow in a vascular channel by Doppler Techniques has an assembly of electro-ultrasonic transducers which direct ultrasonic radiation to a zone spaced from the assembly and receive radiation reflected therefrom. The transducers are spaced apart and capable of providing two radiation beam paths from transmitting to receiving transducers after reflection from the zone. The transducers are directed such that part of one of the beam paths forms an acute angle with the direction of blood flow and part of the other beam path forms an obtuse angle with the direction of blood flow. The reflected signals are shifted in frequency by Doppler effect and their instantaneous difference frequency is monitored and expressed directly in terms of velocity.