The seminar will address the calculation of evanescent states in quasi-one-dimensional quantum wires in the presence of Rashba spin-orbit interaction. We emphasize how the coupling of longitudinal and transverse motions introduced by the spin-orbit interaction leads to a nontrivial behaviour of the evanescent mode wavenumbers and wavefunctions. The dispersion relations are given for some selected cases, illustrating the feasibility of the proposed computational method. As a practical application, we discuss the solutions for a wire containing a potential step.