An approximate method for describing radiation transport is derived. Photoelectric effect and Compton effect are assumed to be the only mechanisms affecting the transport. Thus the method is restricted to the x‐ray and low‐energy gamma‐ray region of the electromagnetic spectrum. Further, the radiation is assumed to be a collimated beam incident normal to a homogeneous semi‐infinite slab. The method described goes one step beyond the classical ``straight‐ahead'' approximation used in the theory of gamma‐ray attenuation. Because of the assumptions used in obtaining the solution, the expressions derived can most appropriately be applied for the case where Compton scattering is near isotropic (relatively low energies) and where the photoelectric cross section is larger than the Compton cross section.