In this study, an attempt is made to develop a model to analyse the anisotropic magnetoresistance in ferromagnetic metal films. In the model, the change in resistivity due to the changes in the scattering processes of the conduction electrons on applying an external magnetic field is proposed to be proportional to the spin–orbit interaction energy ΔU$_{SOI}$ = μ0μM/2. Expressions are developed which relate the resistivity of the sample under an applied external magnetic field to its initial resistivity, current density, conduction electron magnetic moment,sample length, saturation magnetisation, remanence magnetisation, coercive field and external magnetic field. The equations obtained agree well with the experimental anisotropic magnetoresistance data of the ferromagnetic films.