A simple semi-empirical formula has been obtained for the whole-atom integral incoherent scattering cross sections of elements for gamma rays in the 300- to 1250-keV energy region by studying the energy dependence of the experimentally obtained incoherent scattering cross sections of elements in the 279.2- to 1330-keV energy region. The values of the incoherent scattering cross sections evaluated using this formula are found to be in good agreement with the theoretical values compiled by Hubbell et al.