AbstractTreatments of the differential dose albedo of gamma rays on concrete have supposed that the albedo value is a function of the energy of the incident gamma radiation, the polar angle of incidence, the polar angle of reflection, and the azimuthal angle of reflection. It is demonstrated here that, if certain assumptions (which appear reasonable) are made regarding the mechanism of reflection, it is not necessary to investigate variations in albedo with azimuthal angle of reflection. Once differential dose albedo has been determined for a complete set of incident and reflected polar angles with zero azimuth, albedo at any azimuth can be derived by a suitable transformation.