This paper describes a model for the non-linear magnetomechanical coupling in new highly magnetostrictive materials. This model is devoted to the Computer-Aided Design of magnetostrictive devices. It is based on an iterative process of successive magnetic and mechanical computations bv ( I the Finite Element Method. Magnetic and mechanical quantities are still coupled by the iterative process. As a matter offact, the use of experimental data through the Surface Spline Method allows the introduction of the magnetomechanical coupling. The experimental data are collected from a specially designed sample holder devoted to the static characterization of Terfenol-D rods. Comparisons between numerical outputs from the model and the experimental data reveal that the model is quite powerful to describe the magnetomechanical coupling in highly magnetostrictive materials as Terfenol-D. Otherwise, the proposed model has been extended to take into mcount the magnetostrictive effect in microsystems using highly magnetostrictive thin films. Numerical computations provide in this case coherent results and show that it is able to describe the global behaviour of highly magnetostrictive microsystems.