Tests are reported on two thickness of square hollow cross-section mild steel tubes under lateral quasi-static and dynamic loading at two spans and under fully-clamped and simply-supported end conditions. The overall purpose was to understand the collapse mechanism and the relationship between energy absorption and tube deflection. The dynamic tests were carried out at impact velocities upto 6 m/s using a cylindrical steel indentor. The finite element code DYNA3D was used to conduct numerical simulations based on the experiment setup. Overall, the numerical simulations predicted the deformed shape of the tube well and gave accurate estimates of the force and velocity time histories of the simply supported tubes. The difference in both the mode of deformation and the energy absorption rate between the quasi-static and these relatively low velocity dynamic tests was quite small and the quasi-static results could therefore be used with some confidence to approximate the dynamic response.