Abstract: In a method for determining the propagation speed of ultrasonic radiation in a layer of tissue located in front of a structure reflecting ultrasonic radiation, wherein ultrasonic radiation is transmitted from a transmitter arranged immediately outside the layer of tissue through the layer of tissue onto the structure, and the ultrasonic radiation reflected at the structure is received with a receiver arranged immediately outside the layer of tissue, in order to improve the accuracy of the determination of the speed of propagation, it is proposed that the ultrasonic radiation be transmitted in the form of ultrasonic pulses, and the transit times t1 and t2 of the ultrasonic radiation pulses between transmission and reception be determined for at least two different spacings l1 and l2 between transmitter and receiver, and the propagation speed of the ultrasonic radiation in the layer of tissue be calculated from the two spacings l1 and l2 between transmitter and receiver and from the two transit times t1 and t2.