Continuing to the previous chapter (Chap. 26 ), in this chapter, corresponding to Chap. 23 for the nonrelativistic case, we derive the basic equations for relativistic radiation hydrodynamics within the framework of special relativity. In addition, we show several topics on the radiation hydrodynamics in the relativistic regime, relating mainly to radiation drag. We also examine relativistic radiation hydrodynamical (RHD) flows, and relativistic radiative shocks in some details.