Variation of &bgr;‐ray backscattering with the atomic number of target material has been studied using thick targets of polythene, aluminum, iron, copper, zinc, tin, silver, tungsten, and lead for five &bgr; emitters, viz.,35S,147Pm,204Tl,32P, and90Sr‐90Y. Effects of geometry and &bgr;‐ray end‐point energy have been investigated using a reflection geometry in which the geometry factors were varied by more than 40 and &bgr;‐ray energy varied over a range 0.167–2.27 MeV. It is found that the mean value of the index ofZdependence of &bgr;‐ray backscattering is 1.840.05 over these regions of geometry and energy. Deviations for soft &bgr; emitters have been confirmed as due to air absorption. The importance of these results in studies of two‐component systems is emphasized.