This study was conducted to investigate the effects of plastic deformation on magnetic Barkhausen noise (MBN) signals in mild steel. A number of mild steel samples were subjected to different degrees of uniaxial plastic deformation up to 30&percent; strain. Angular MBN measurements were done on those samples. The results indicated that plastic deformation introduces a magnetic easy axis depending on the degree of plastic deformation. A significant progression towards magnetic isotropy (no magnetic easy axis) was observed after heat‐treating the samples at low temperatures 450° C, 475° C, and 500° C. The activation energy associated with the anisotropy decrease was calculated from the low temperature annealing results using an Arrhenius‐type analysis. This was found to be 99 Kcal/mol, which is consistent with recovery‐type processes. © 2003 American Institute of Physics