The theory of heat conduction in the presence of radiation inside a transparent body is developed, and a general equation of heat transfer has been obtained. The general equation of heat transfer in the stationary state is solved for four special forms of bodies, namely, plane, circular cylinder, sphere, and prolate spheroid. In the plane problem, numerical calculation is carried out, with results. differing frpm those obtained previously by Kellet. It is pointed out in the present paper that Kellet has neglected the property of radiation emitting in all directions, but only considered the radiation along the direction of temperature change, so that the equation of heat transfer obtained by Kellet is different.