One of the most important effects of torsion, which can be used in many technical applications is the modification of the initial configuration of bar. Relating to this effect, the theories of the Mechanics and Strength of Materials reffer, only, to the helical orientation, of the generatrixes of bars and the warping of the noncircular cross-sections. The present paper analyses the changes of the configuration of bar in its axial direction plastic torsion.