Various parameters of dosimetric importance such as effective atomic numbers (Zeff) and electron densities (Nel) of nucleobases in DNA have been calculated for the total and partial photon interaction processes in the wide energy range of 1keV–100GeV. The variations of Zeff and Nel with energy are shown graphically for all partial and total interaction processes and are found to be similar. Up to 10keV, Zeff and Nel show a sharp increase for cytosine-guanine and thymine-adenine whereas for all the other nucleobases, it is almost constant. Then there is sharp decrease in Zeff and Nel with energy up to 100keV for all the nucleobases. From 100keV to 6MeV, Zeff and Nel are almost independent of energy. From 6MeV to 100MeV, there is regular increase in Zeff and Nel with photon energy. Above 400MeV, Zeff and Nel remain almost constant. The obtained results are due to the dominance of photoelectric absorption, Compton scattering and pair production in different energy regions as respectively stated above and their dependences on the chemical compositions of the interacting media.