The method and apparatus are for bending or straightening a material such as a rail. A simple form of the apparatus comprises two spaced contact members for contacting the rail, and a rail lifting member located between these points arranged to lift the rail between the two points, the lifting member being arranged to engage the head of the rail. A preferred method comprises applying a load to the material and, while the load is applied, continuously or periodically measuring the load applied and the displacement of the material relative to the datum, establishing from the measurements a load at which the plastic component of the total deformation measured is equal to the predetermined deformation from the datum, and then removing the load.