Compositional changes of binary alloys and compounds have been observed (by Rutherford backscattering techniques) as a result of rare‐gas sputtering in the energy range 20–80 keV. After sputtering, the heavier components were generally found to be enriched in a surface layer whose thickness corresponded approximately to the range of the sputtering ion; the compositions of these enriched surface layers were independent of the mass and energy of the sputtering ions. This phenomenon of surface layer enrichment is interpreted as due to preferential sputtering from the surface in combination with defect‐enhanced diffusion.