Straightening of components after heat treatment is a common procedure in the industry. Typically, elongated components such as shafts and bars are distorted after heat treatment in such a way that straightening is necessary to obtain the desired shape. The straightening operation leads to local plasticisation of the component. This has an effect on for example the residual stress state and the hardness, parameters with strong influence on the fatigue strength of the component. The objective has been to evaluate the influence of straightening on bending fatigue properties, the residual stress state, microstructure and hardness of induction hardened test bars. Straightening was made using three point bending on cylindrical shafts. The residual stress state and hardness were evaluated, before and after straightening. Fatigue testing was performed in three point bending, after rotating the shaft 60 ° after straightening, i.e. towards 120° direction. FEM-simulation of straightening was performed in order to formulate guidelines for straightening. The simulations were performed on a virtually induction hardened shaft of the same dimensions as used in the experiments. It was concluded that straightening affects the residual stress state along the entire circumference of a component. The fatigue strength at 120° was 7% lower after straightening with 80 kN load and 20% lower after straightening with 97 kN load. Residual stresses were affected differently around the perimeter of the shaft. At the point of straightening force application (0°) the compressive residual stresses after heat treating turned to tensile. At the opposite side at 180° the residual stresses turned more compressive than before straightening. At 120° and 240°, the stresses were negatively affected and the residual stresses turned less compressive. The higher of the two straightening forces had even more negative effect on residual stresses. The simulations showed similar changes in residual stresses as were experimentally found. It was concluded that reversed straightening should be avoided and that at higher forces used with combined straightening operations at an angle compared to the desired straightening direction is preferable if larger corrections needs to be done.