The paper presents a simplified method for modelling of permanent of permanent deformations of unbound granular layers. This method is based on three steps: fist, the material is characterized using repeated load triaxial tests, with different stress levels. Then, the test results are analyzed using a model of prediction of permanent deformations as a function of maximum applied cyclic stresses and numbers of load cycles. Two different models can be selected at this stage: an empirical relationship and an elastoplastic model. Finally, a finite element analysis with the program CESAR-LCPC, is used to determine the stress distribution in the pavement. The stresses calculated at different points in the structure allow the permanent vertical strains at each point to be determined, be applying one of the selected permenent deformation models. Finally the permanent strains are integrated along the vertical direction to obtain the vertical displacements in the structure (i.e. rutting of the layer). An example of application of the method is presented