A study has been made of the friction and hardness of chromium implanted mild steel. Ion implantation was performed with doses of 1×1015-1×1017ions/cm2 at 50-150keV. energies The friction coefficients and the Vickers hardness of Cr-implanted specimens were measured with a Bowden-Leben type friction testing machine and a micro-Vickers hardness tester, respectively. All tests were carried out at atmospheric room temperature. The friction coefficients had a tendency to decrease as the Cr fluence increased, but were independent of the acceleration energy. As the dose increased, the Vickers hardness increased at a lower normal load than 10gf, Concentration profiles of Cr were measured by secondary ion mass analysis in order to investigate the surface layer depth which contributes to friction and hardness properties. The Cr profiles showed abnormally high concentrations of oxidized chromium down to 200Å from the surface, not predicted by the range theory, and which are supposed to cause a decrease in the friction coefficients and an increase in the hardness.