Averaged forces acting on a relativistic particle in a waveguide R. A. H. Castillo, V. P. Milantiev Russian University of People’s Friendship, 6 Mikluho-Maklay str., Moscow, 117198, Russia E-mail: vmilantiev@sci.pfu.edu.ru The general expressions for the components of the averaged (ponderomotive) force acting on a relativistic charged particle in the field of the waveguide Hmn-mode are obtained. <...> It is shown that, in general, the average force along the direction of wave propagation is equal to zero. <...> However, the averaged force can differ from zero under specific conditions of the particle injection into the wave. <...> Показано, что в направлении распространения волны усредненная сила, в общем, отсутствует. <...> Однако при определенных условиях ввода частицы в поле волны усредненная сила может быть отличной от нуля! <...>