Аннотация:This paper is devoted to experimental investigation of regular trends of acoustic waves propagation and glancing reflections in XY plane of TeO2 single crystal. The unusual "backward" reflection of the acoustic waves from a side border of the crystal when the phase velocity of sound is directed along the border has been observed. All experimental results were in good agreement with the predictions of theory, related to the magnitudes of the phase and group velocities of ultrasound as well as to the acoustic energy walkoff angles in the crystal.