We use the generalized hydrodynamic method in order to describe the macroscopic dynamics of polymeric side‐chain liquid crystals. The hydrodynamic method uses only general symmetry arguments and irreversible thermodynamics to establish phenomenological dynamic equations. In the present case this method has to be generalized by taking into account not only the true hydrodynamic variables, but also some slow relaxational variables, which are slow enough to be relevant for the usual hydrodynamic frequency range.