DLC gradient coatings had been deposited on Ti6A14V alloy substrate by plasma source ion implantation-ion beam enhanced deposition method and their friction and wear behavior sliding against ultra high molecular weight polyethylene counterpart were investigated. The results showed that DLC gradient coated Ti6A14V had low friction coefficient, which reduced 24, 14 and 10% compared with non-coated Ti6A14V alloy under dry sliding, lubrication of bovine serum and 0.9% NaCl solution, respectively. DLC gradient coated Ti6A14V showed significantly improved wear resistance, the wear rate was about half of non-coated Ti6A14V alloy. The wear of ultra high molecular weight polyethylene counterpart was also reduced. High adhesion to Ti6A14V substrate of DLC gradient coatings and surface structure played important roles in improved tribological performance, serious oxidative wear was eliminated when DLC gradient coating was applied to the Ti6A14V alloy. (C) 2004 Elsevier B.V. All rights reserved.