Frictional heat always accompanies the friction process. It can be assumed that anisotropic friction induces anisotropic frictional heat for crystals, composites and materials with microstructure. Using a thermodynamical approach, a general method for deriving constitutive equations for frictional heat is presented. The directionality of frictional heat is described by a heat intensity function depending on the sliding direction. Symmetries and particular anisotropic heal directions are investigated. Examples illustrate different types of frictional heat anistropies.