The paper examines regular trends of light diffraction by ultrasound propagating in media possessing anisotropy of elastic properties. The analysis is carried out on base of the single crystals of tellurium dioxide TeO2, calomel Hg2Cl2 and tellurium Te. The particular crystalline media have been chosen due to the extremely large angles between phase V and group Vg velocities of the acoustic waves in the materials. In X-Y planes of the crystals, the obliquity angle may exceed the value φ > 45°. It is shown that the strong anisotropy of the elastic properties influences on the process of light and sound interaction. In the case of Bragg regime of light diffraction, the diffracted beam intensity I1 and the acoustic frequency bandwidth of diffraction Δf in the anisotropic crystals differ from the corresponding efficiency and the bandwidth in glass materials. The paper considers features of the acousto-optic interaction originating from the presence of the elastic anisotropy.