The Auger (autoionization) spectra produced by bombarding a magnesium target with argon and neon ions of energy in the range 200 eV-5 keV x e reported. The observed spectra of both gases contained considerable fine smctuce broadly similar to that observed in spectra from aluminium and silicon targets. The Mg spectra contained structure not previously reported, which could be indexed as pan of 3 series of transitions from M excited state in M i ' to states at and above the ground state in Mg+. The variation of the heights of the main peaks was examined as a funcdon of incident ion energy. The graph of peak height against incidence energy showed 3 sharp maximum for Ar while this was not the case for either Ne or Mg.The m e gas Auger peaks increased in energy with increasing incident ion energy and the shift could be explained in terms of a simple Doppler madel appropriate to the strongly fonvard scattered experimental conditions used here. No systematic vatiation in the energies of the Mg peaks was observed.