Ions with a kinetic energy of the order of 1 KeV are very effective in removing adsorption layers from solid surfaces. Ion induced desorption (or sputtering) is therefore widely used for surface cleaning, but the number of systematic studies is still not very large. A primary ion beam impinging on a surface produces a variety of signals which can be exploited to study the desorption in detail. For instance, this can be done by using low-energy ion scattering (ISS), ion produced photons (IPP) or secondary ion mass spectroscopy (SIMS). The usefulness of these methods, particularly ISS, for investigating desorption phenomena is demonstrated for various overlayers on metal surfaces. The special aspects arising from the application of this method for monitoring the surface composition are discussed. Quantitative desorption cross-sections have been obtained and their dependence on several important parameters, such as atomic masses, impact angle, surface crystallography, surface binding energy, etc. has been studied. From these results insight into the mechanism of ion impact desorption is gained. In many cases it can be explained by assuming a series of binary collision processes. This is supported by comparing the experimental results with numerical calculations. For some overlayer systems more complicated mechanisms must be invoked to explain the experimental findings. The role of recoil implantation of surface atoms by the primary beam is also discussed.