The stress wave caused by a longitudinal impact at the end of a cylindrical bar has been analyzed in the case where the impact velocity is large enough to produce plastic strain. The theory gives a method for computing the stress distribution along the bar at any instant during impact. It is shown that for a given material, there is a critical impact velocity such that when subjected to a tension impact with a velocity higher than the critical, the material should break near the impacted end with negligible plastic strain. An experimental investigation was made concurrently with the theoretical study. Some of the most significant experimental results are presented in this paper.