The aim of this paper was the application of the ultrasonic method to determine the concentration profile of suspensions during their sedimentation. The model of wave propagation in the suspensions was presented, on the basis of which the relations between the wave velocity and the volume fraction and between the attenuation coefficient and the volume fraction of the suspension were determined. The experimental tests were carried out on the peat suspension in water both in the sedimentation column and in a tank at the direct contact of the ultrasonic heads with the suspension.