An asymptotic theory of resonance interaction of shearand bending modes in a non-uniform Timoshenko beam Maria V. Perel, Ignat 17. Fialkovsky Physics Faculty, St.Petersburg University, K.ussia, Aleksei P. Kiselev Institute of Mechanical Engineering, Vasilievsky Ostrov Bolshoy Prospect 61, S t.Petersburg 199178, RussiaPropagation of modes in a smoothly non-uniform Timoshenko beam is considered. We present an asymptotic theory of interaction of two modes which phase velocities intersect at a single point and are non-tangent there. Highfrequency regime in the lime-harmonic case and propagation of discontinuities are both considered.