Static and dynamic strength of thin-walled mild steel box columns subjected to axial loading is studied both theoretically and experimentally. A series of impact tests was made using a pendulum hammer experimental facility. The computed dynamic crushing force was always higher than the corresponding static value and the ratio of the two forces /dynamic correction factor/ was shown to be an increasing function of the initial impact velocity. A simple theory is used to predict the average force level and energy absorption of dynamically crushed columns. A good agreement between the theory and present experimental results as well as those of other authors was obtained. A significance of an averaging procedure for a proper interpretation of test results is emphasized. The results obtained are applicable in the preliminary design of energy absorbing members of crushworthy buses and trucks.