A model for the interaction between a surface acoustic wave (SAW) and a surrounding gas in the free-molecular mode along the SAW length is proposed. A new boundary kinetic effect is predicted based on this suggested model. This effect is caused by SAW propagation and similar classical boundary effects, such as thermal or diffusion sliding of the gas. A functional dependence of the effect upon the gas and the SAW parameters is presented. The sliding is brought about by the nonsymmetrical, angular restriction of the flow due to the deformation of the solid surface by SAWs.