In seismic zones the use of inclined piles, to withstand horizontal forces, is not recommended by modern seismic codes for two main reasons: they may induce large forces on the pile cap and permanent rotations may arise during strong earthquakes. However recent numerical studies demonstrate that inclined piles may sometimes have a beneficial effect on the behaviour of pile groups subject to earthquake loadings and therefore, further investigations are needed to clarify the role of inclined piles on the seismic behaviour of superstructures and foundations.This paper focuses on the dynamic stiffness and dimensionless displacement response factors of pile groups with inclined piles. A numerical model is obtained by generalizing a previously developed model for the kinematic interaction analysis of vertical piles. The model is validated comparing results with more rigorous ones available in the literature and by means of 3D finite element models. Impedances and kinematic response factors of some pile groups with inclined piles are shown and compared with those relevant to vertical piles showing effects of inclination on the group stiffness and kinematic response.