Abstract The temperature and pressure dependence of the Mössbauer γ-ray energy shift of 57Fe in natural iron, has been analysed taking into account both the second order Doppler shift (S.O.D.) and the isomer shift (I.S.) contributions. The variation of the S.O.D. both with temperature and pressure, is calculated from the experimental phonon frequency distribution and that of the I.S. has been evaluated using the scaling with volume of the direct 4 s electron density, |ψ 4 s (O)| 2, as well as the indirect 3 s electron density, |ψ 3 s (O)| 2, at the nucleus; and including the electron transfer from the 4 s to 3 d band. Data from pressure stuides have been utilized to evaluate two parameters; the proportionality constant between the I.S. and |ψ(O)| 2 and the number of electrons transferred with change of volume from the 4 s to 3 d band. It appears that in the case of a magnetic lattice such as iron, the temperature dependence of the S.O.D. calculated from the phonon distribution is inadequate to completely explain the observed energy shift, that instead a contribution arising from magnetization seems important; as is to be expected theoretically. On including a term proportional to the magnetizations, the calculated temperature variation of the I.S. compares well with that determined by us from the pressure studies of the γ-ray energy shift.