The investigation of a nonreciprocal effect for the example of collinear acousto-optic interaction is presented. It is shown that this effect influences the parameters of diffraction and the operation of modern acousto-optic devices, particularly acousto-optic tunable filters (AOTFs), at the frequencies of ultrasound of about 1 GHz and higher. The analytical expressions are obtained, and the calculations of the nonreciprocal effect for different acousto-optic materials are carried out. The effect is registered experimentally at the optic wavelengths of 633 and 532 with the help of a collinear AOTF on the base of a lithium niobate crystal.