The consequence of imposing an axisymmetric travelling-wave disturbance on the Poiseuille flow between two concentric cylinders is examined. A nonlinear analysis is taken, using perturbed bifurcation and singular perturbation theory, to determine how resonant wall oscillations affect flow stability. Subcritical, stable, finite-amplitude perturbations to the basic Poiseuille flow are found and conjectures on their significance are given.