The ionization rate of neutral deuterium due to charge exchange with iron impurities in tokamak plasmas is theoretically investigated. The iron ions are assumed to be in coronal equilibrium, and three distinct categories of neutral-deuterium energy are considered. The ionization rate of each category due to charge exchange with the iron ions is compared with the sum of the ionization rates due to electron and ion collisions and charge exchange with the plasma ions. The contribution of iron ions to the total ionization rate of neutrals is found to be negligible for neutral energies of the order of 5 eV/amu, as long as the total iron density is less than 1% of the peak electron density. Their contribution becomes significant for neutral energies of 1 keV or higher and is comparable to those of plasma electrons and ions for neutral energies of the order of 20 keV/amu, for the same density ratio.