The use of ion beams to produce modified surfaces on the micro- and nano-scale is described and the advantages of using ion beams to gain a better fundamental understanding of the growth process are outlined. Examples of current projects are given and include recent results on nc-TiN/a-Si3N4 nanocomposites, Ti-Cr-N coatings, the control of stress in oxide coatings, production of surfaces with getter pumping properties and the effects of surface modification on biocompatibility. For the nanocomposite films it is shown that hardness values increase with substrate temperature and increased levels of ion-assistance. Ti-Zr and Ti-Zr-V coatings have been produced to evaluate their getter performance and preliminary results show that these films can be re-activated at temperatures of 350°C. Ion-assisted deposition of SiO2 films has been shown to reduce the stress in these films by a factor of 2. Biological cell-surface interaction studies on surfaces modified using ion beams are reported and show that cell proliferation is influenced both by chemical changes and sometimes by the surface topographical features.