The physical characterization of thin films has been greatly enhanced in recent years by the deployment of surface analysis techniques. In particular, the use of low energy ion beams to remove successive surface layers by sputtering has enabled fine scale composition-depth profiles to be obtained. However, although the technique is extremely important, artefacts can occur because of the non-uniform erosion of the surface during sputtering which may cause an uneven topography in the ion-etched crater and hence an uncertainty in the depth resolution of the technique. One mechanism for this effect is linked with the inducement of structural damage in the film during bombardment since this produces locally different sputtering yields and hence induces roughness. Field ion microscopy was used to investigate the effect of low energy (1–3 keV) inert gas ion bombardment of tungsten surfaces. The experiments were performed with ion doses in the range 10 15–10 17 ions cm -2, thereby enabling the precise nature and depth of the surface and subsurface damage to be determined. The results allow us to draw general conclusions which should help to minimize the deterioration of depth resolution of composition-depth profiles.