Abstract—The aim of this work is to study and compare various approximations for the system of radiative heat transfer equations (TEs) in optically dense and transparent media. For this purpose, in optically dense media, asymptotic analysis is used; and in optically transparent media, an approach that allows reducing the solution of diffusion equations to solve a kinetic equation. The performed studies enable us to conclude that in optically dense media the solutions in the considered approximations tend to the solution of the kinetic equation with increasing optical thickness. This follows from the asymptotic analysis. In optically transparent media, coincidence with the solution of the kinetic equation is only possible in the quasi-transfer and quasi-diffusion approximations.