The heat dissipation function for polarizable anisotropic media in which phenomena of dielectric relaxation occcur is derived as a generalization of the heat dissipation function studied in the case that the media are isotropic. The methods of non-equilibrium thermodynamics are used. It is seen that the linearization of the theory leads to a dielectric relaxation equation for anisotropic polarizable media which has the form of a linear relation among the temperature, the components of the electric field vector and of the total polarization vector, the first derivatives with respect to time of the components of these vectors and of the temperature and the components of the second derivative with respect to time of the total polarization vector. It is shown that the heat dissipation function is due to irreversible phenomena of viscous flow, electric conduction and dielectric relaxation. Finally, the obtained results are applied to the particular cases of Debye media and De Groot-Mazur media.