The paper presents the dynamic modeling of Multi-phase Hybrid Stepper Motors (MHSM). The model is as general as possible and it is obtained using a Lagrangian approach in the frame of the Power-Oriented Graphs (POG) technique. The obtained dynamic models can be directly implemented in Simulink and they can be used to simulate also the Permanent Magnet and the Variable Reluctance stepper motors. Some simulation results are finally presented.