Biomedical grade (>99.5% purity) alpha-alumina has been implanted with carbon ions at fluences ranging from 5 x 10(16) to 5 x 10(17) C ions/cm(2) at an ion energy of 75 keV. The surfaces of the alumina have been examined in cross-section using transmission electron microscopy (TEM) and the data correlated with both nanohardness measurements and computer based simulations (Transport and Range of Ions in Matter, TRIM). TEM examination of the implanted surface has demonstrated the formation of a sub-surface amorphous layer as well as other microstructural modifications that are characteristic of ion damage. The nanohardness of the near-surface alumina was determined as a function of depth and was found to be strongly dependent on the fluence used.