An ultrasonic flow meter has two ring-shaped piezoelectric transducers (1, 2) comprising ring-shaped piezoelectric elements or being composed of piezoelectric sections. Both the transducers (1, 2) are arranged in axial symmetry in a distance to each other. One of them is operated as the ultrasonic transmitter and the other one as ultrasonic receiver. The medium, the flow rate of which is to be measured, flows through both the transducers (1, 2) essentially parallel to the axis (L--L).