The microstructure of alumina after Ti ion implantation has been investigated. A metal vapour vacuum arc (MEVVA) ion source was employed to implant Ti ions into alumina with doses of 7.6 x 10(16) and 3.1 x 10(17) ions/cm(2) at 40 kV. Scanning electron microscopy (SEM) of the irradiated surfaces revealed topographical changes, which were dependent on dose. The implanted layer was also characterised by Rutherford backscattering (RBS) and cross-sectional transmission electron microscopy (XTEM) which showed the lower Ti dose resulted in a highly defective surface layer. In contrast, TiO2 precipitates in an amorphous matrix were observed at the higher dose.